I m

UNIVERSITY RESEARCH INITIATIVE

I'-

CENTER FOR ADVANCED ELECTRICAL

AND STRUCTURAL POLYMERS

[AFOSR-90-0150[

i 1 March 1990 - 28 February 1993

I DTIC

FINAL REPORT ' 3

I

3 Frank E. Karasz

Department of Polymer Science & Engineering

University of Massachusetts

Amherst, MA 01003

I3 '29 7l|UA 93 12 6 030

REPORT DOCUMENTATION PAGE I No.m 070A-ro8d.. . i __ . 1- .o. 0"0• 01" IPudirc to"orfeg burden for this, ,ollechio o~f ifoirmatio i$ eHlMA reOd it iverage I hour pe respoonse i .cludi ng thei time for reviewing instrut ions., SaFC ht ftg e~nt ing data %ouarces.gath eiring and maintain in the dita meeded, and co'"Oetmg "nd 'kewd""g' •he ,:oliecl•n ol nforrmatiorn Send comntent$ regarding this DbuJfft eitirmleate r any other aspoect of thiscolie tion of infor•m-i,0on. including sugglestions torfedum jthis • en to Wash.ngi, n Headiquar tefs Services, Dar, cO ave for infoirial,on operations• and Reportts. 12 15• jefferson,

1. AGENCY USE ONLY (Leave blank) O DATE 3. REPORT TYPE AND DATES COVERED

15 October 1993 Final mar. 1990 - 28 Feb. 19934. TITLE AND SUBTITLE "S. FUNDING NUMBERS

Center for Advanced Electrical and Structural Polymers 61103D, 3484/CS

6. AUTHOR(S - 3 /

Professor Frank E. Karasz

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) i-.PERFORIVIING ORGANIZATION.PREPORMTN OUBRGNZIN

Dept. of Polymer Science and Engineering REPORT NUMBER

University of MassachusettsAmherst, MA 01003 A .•

9. SPONSORING / MONITORING AGENCY NAME(S) AND ADORESS(ES) 10. SPONSORING/ MONITORING

AFOSR/NC AGENCY REPORT NUMBER

110 DUNCAN AVENUE SUITE B115BOLLING AFB DC 20332-0001

11. SUPPLEMENTARY NOTES

.12a. OISTRIBUTION / AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

APPROVED FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITEDi

13. ABSTRACT (Maximum 200 words)Research in the U.R.I. has been org nized into five thrust areas each

comprising collateral and coordinated investigations in three dep aments at UMass and at WrightState University, Foster Miller Inc. and MIT. Electrical properties of IL-conjugated polymers are thefocus of one thrust and are defined in terms of their structure-pro 'erty relationships as well as longterm applications. A prototypical polymer has been poly-p-phenylene vinylene. A second thrust hasconcentrated on non-linear optical effects in n-conjugated and si.de chain liquid crystal polymerscontaining chromophoric mesogens which have been synthesized[ and characterized, as have low-molecular weight model compounds of systematically varying structure. The third thrust has focusedon polymer blends and alloys including high temperature novel pro~essible systems for application inextreme conditions. Miscibility studies in conventional model polynqers has continued to yield insightsinto the fundamental principles underlying polymer-polymer interactions. A computer simulationproject has complemented these studies. The thrust on novel #nacromolecular architecture andcharacterization has produced a range of new systems and technques including measurements of

polymer dynamics in constricted geometries, and detailed fine-ýtructure investigations of blockcopolymers. A thrust on new processing technologies has largely cehtered on the FMI initiatives withrespect to novel approaches for high temperature polymer blend nfelts.

14. SUBJECT TERMS 15. NUMBER OF PAGES

electrical properties, non-linear optical effects, polymer 76blends and alloys, macromolecular architecture and characterization 16. PRICE CODE

S17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACTOF REPORT OF THIS PAGE OF ABSTRACT

UNCLASSIFIED UNCLASSIFIED UNCLASSIFI]ED UNCLASSIFIED

NSN 7540-01-280-5500 I Standard Form 298 (Rev 2-89)Prescribed by ANý,I Sid 139-18298 102

III

UNIVERSITY RESEARCH INITIATIVEIn CENTER FOR ADVANCED ELECTRICAL

AND STRUCTURAL POLYMERS

Accesion For

NTIS CRA&IU DI-TC TAB3

AFOSR-90-0150 UJ;.•, o;ced

1 March 1990 o 28 February 1993 .

FINAL REPORT .

Frank E. KaraszDepartment of Polymer Science & Engineering

University of MassachusettsAmherst, MA 01003

Ii ~mm iDI

I

I ACKNOWLEDGEMENT

IThe Principal Investigator would like to express his sincere thanks to Dr.

Donald Ball, Director of Chemical Sciences, Air Force of Scientific Research, to the

I late Dr. Donald R. Ulrich, Senior Program Manager, Directorate of Chemical

I Sciences, to Dr. Charles Y-C Lee, Senior Program Manager, Directorate of

Chemical Sciences and to Dr. B. Wilcox, Assistant Director, Material Science

Division, Defense Advanced Research Projects Agency, for their unfailing

I cooperation, help and courtesy extended to him during the period of this grant.

iIIIIIi

IIm m m ~ m ~ mmm mmm m m

F 3

CONTENTS

I. TITLE

SII. PRINCIPAL INVESTIGATOR

I III. GRANT NUMBERS/DATES

IV. FACULTY ASSOCIATES (UMASS) AND SENIOR RESEARCH

PERSONNEL

V. JUNIOR RESEARCH PERSONNEL

VI. EXTRA-MURAL SUBCONTRACTORS

VII. ABSTRACT OF ACCOMPLISHMENTS

VIII. DESCRIPTION OF RESEARCH UNDERTAKEN

APPENDIX 1 - FOSTER MILLER INC.

APPENDIX 2 - WRIGHT STATE UNIVERSITY

APPENDIX 3 - MASSACHUSETTS INSTITUTE OF TECHNOLOGY

13L PUBLICATIONS

4

I. TITLE: Center for Advanced Electrical and Structural Polymers

II. PRINCIPAL INVESTIGATOR: Dr. Frank E. KaraszPolymer Science & EngineeringUniversity of MassachusettsAmherst, MA 01003

III. GRANT NUMBER:

AFOSR-90-0150 March 1, 1990 - February 28, 1993

TV. FACULTY ASSOCIATES, UMass: Professor K.H. Langley,Physics & AstronomyProfessor W.J. MacKnight,Polymer Science & EngineeringProfessor P. Lahti,Chemistry

SENIOR RESEARCH PERSONNEL:Dr. Pellegrino Musto Dr. Ray McCoyDr. Hai tmut Fischer Dr. Stephen O'DonohueDr. David Rice Dr. Limeng WuDr. Zhikuan Chai Dr. Antonin SikoraDr. Steven Rutt Dr. Jorg KresslerDr. Alan Waddon Dr. Peter CifraDr. Ruona Sun Dr. Iwao TeraokaDr. Corrie Imrie Dr. Laszlo Litauszki

I Dr. Sossio Cimmino Dr. Paul Bristowe (MIT)Dr. Feng Gao (WSU) Dr. Raymon Albalak (MIT)Dr. B.R. McKellar (WSU) Dr. Maria Goncalves (MIT)

SDr. Weipang Zhang (MIT) Dr. Gia Kim (MIT)Dr. Kent Blizard (FMI) Dr. Tom Fusco (FMI)

V. .JUNIOR RESEARCH PERSONNEL:J. Simpson Y. GuoW. Nachlis F. DentonZ. Peredy D. ChoiM. Starkweather A. SarkerS. Li J. NeillM. Patel (WSU) R. GregoriusS. Shanbag (WSU) H. Prijaya (WSU)W. Qian (WSU) J. Lin (WSU)M. Coffey (WSU) J. Chen (MIT)S. Gido (MIT) D-K. Ding (MIT)

5

Peter Schuler (FMI) Bill Slager (FMI)John Larouco (FMI)

VI. SUBCONTRACTORS: Profs. W.A. Feld, J.J. Kane;Wright State University,Dayton, Ohio (WSU)

Mr. R. Lusignea, Dr. M. Druy;Foster-Miller, Inc.,Waltham, MA

Prof. E.L. Thomas,M. I. T.Cambridge, MA

6

VII. ABSTRACT OF ACCOMPLISHMENTS

This report presents in some detail the accomplishments of the last twelve

months at the URI Center of Advanced Electrical and Structural Polymers at

UMass. In addition this Final Report provides an overview of achievements

during the three year period of the grant. In particular, the total output of

publications over the period of the grant are listed.

Research has been organized into five thrust areas comprising collateral and

coordinated investigations in three departments at UMass and at three extra-

mural sub-contractors. Electrical properties of polymers are the focus of one

thrust and these have covered a wide range of simple and increasingly complex x-

conjugated systems defined in terms of their structure-property relationships as

well as long terii applications. A prototypical polymer has been poly-p-phenylene

vinylene, extensively investigated with respect to its electrical, structural

morphological and other relevant properties. These have been studied using a

wide range of advanced instrumental techniques. A second thrust has

concentrated on non-linear optical effects in i-conjugated systems and has

involved extensive collaboration within and outside the URI. Side chain liquid

crystal polymers containing chromophoric mesogens have also been synthesized

and characterized, as has a wide range of relevant polymers and low-molecular

weight model compounds (WSU) of systematically varying structure. The third

thrust has focused on polymer blends and alloys. Strong collaboration with FMI

and other industrial researchers in the area of high temperature systems had

7

produced a number of novel processible systems for application in extreme

conditions. Miscibility studies in conventional model polymers has continued to

yield valuable insights into the fundamental principles underlying polymer-

polymer interactions and the effect of micro-structure on these properties. These

studies have been complemented by an extensive simulation project which has

shown, inter alia, the effect of the commonly employed mean-field approximation

in this context. The thrust on novel macromolecular architecture and

characterization has produced a range of new systems and new techniques of

which the more recent measurements of polymer dynamics in constricted

geometries is only one example. Another lies in the area of block copolymers for

which detailed fine-structure features have become available in selected systems.

Finally, the URI has incorporated a thrust on new processing technologies which

has largely centered on the FMI initiatives with respect to novel approaches for

high temperature polymer blend melts.

The contents of the five thrusts outlined above have been constantly

modified and allowed to overlap as opportunities arose on the basis of new results.

As always, it was necessary to make choices as funding levels changed and

expansion or curtailment of particular investigations became appropriate. As an

important academic by-product, the URI had considerable direct and indirect

influence on graduate education and available facilities at UMass and at the sub-

contractor sites. Over the course of the three year period some forty or fifty

graduate students and post-doctoral fellows have received at least some direct

8

support from the URI; many more than this have benefitted indirectly through the

ready availability of URI-funded facilities and infra-structure.

9

VIII. DESCRIPTION OF RESEARCH UNDERTAKEN

1. INTRODUCTION

The URI program '. UMass and sub-contractor sites has been

organized as The Center for Advanced Electrical and Structural Polymers which

operated with AM'OSR/DARPA support for a total of 6 years. In the period covered

by this report research was organized into five thrusts:

1. Electrical Properties of Polymers

2. Non-Linear Optical Properties of Polymers

3. Polymer Blends and Alloys

4. Novel Macromolecular Architectures and Characterization

and 5. New Processing Technology.

Each of these thrusts involved collaborative interactions between the PI,

Faculty associates, extra-mural subcontractors and government associates. The

directions of the thrusts evolved and were modified as needed to take into account

new research opportunities and, in later years, contractions necessitated by a

decrease in available funding.

Details of the organizational changes have been given in earlier Annual

Reports.

The URI has had major impact on polymer research at UMass and at the

associated sites. Over the last three years it has been supported 26, fully or in

part, post-doctoral fellows and 23 doctoral students. It has allowed the acquisition

of several major state-of-the art instruments and facilities. In the period covered

10

by this Report one hundred and ten scientific publications have appeared or are in

press, together with a number of patents as a result of URI support.

In the following sections some research highlights pertaining to each of the

thrusts will be described. Chapter IX provides complete details of the scientific

output in terms of publication citations.

2. ELECTRICAL PROPERTIES OF POLYMERS

In this thrust the synthesis, properties and applications of poly-p-

phenylene vinylene and related macromolecules have been the main focus of

attention. PPV is a prototypical n-conjugated chain, synthesized by novel

precursor route, that has been a leading candidate for synthetic metal applications

for a decade. We have studied this system comprehensively including (for

example) the polymerization mechanism, the crystallographic structure,

mechanical properties, electrical properties, copolymers, blends, processing, X"

behavior, electro-luminescence and other photophysical processes (see, for

example, publications 5, 10, 14, 30, 37, 40, 54, 60, 64, 70, 71, 72, 73, 83, 87, 90, 94,

108, Chapter IX). Modified PPV's synthesized here constituted the first report of

soluble macromolecular materials to exhibit blue (474 nm) electroluminescense

and have been the subject of recent intense investigation.

3. NON-LINEAR OPTICALLY ACTIVE POLYMERS

This thrust has comprised three major efforts: a) An extensive synthetic

program at WSU (See Appendix 2 for details.) which has systematically explored a

variety of hetero-atom containing and other structures, including low molar mass

I

model components, and has thereby derived a comprehensive understanding of

structure-NLO property relationships (e.g. 6, 7, 8, 9, 45) b) A synthetic effort at

3 UMass coupled with the electrical property thrust in which n-conjugated

macromolecules based on PPV but involving derivatives, r-opolymers, hetero-atom

analogs, alloys and novel sol-gel glass blends have been prepared and extensively

I studied. Some of these materials have large off-resonance X")'s and this effort

3 could yield materials of high practical applications, (22, 44, 87) c) A third effort

has brought side-chain liquid crystalline materials into this thrust. In this

I program a number of mesogenic units and spacers have been attached to flexible

chain backbones and have been investigated with regard to transitional properties,

structure, alignments, etc.

U All these sub-thrusts have involved extensive collaboration with

3 WPAFB,(84, 88, 103, 104, 107) other URI laboratories and other academic and

industrial organizations.

4. POLYMER BLENDS AND ALLOYS

Much of this work has been described in previous reports. A fraction of this

g thrust has continued the directions of an earlier AF-DARPA program on high

temperature blend systems and there has been a major synthetic effort in the area

I of polyimides of novel structure (63, 100) and blends of polyimides with sulfones,

3 carbonates, etc. This work is closely coupled with the work of FMI (see Section 6

and Appendix 1) who have been able to scale-up some of the blend systems

I developed at UMass, (56).

II

1 12In another facet of this program, the effect of copolymer sequence

distribution on miscibility has been investigated in model systems. It is known for

I example that alternating and random copolymers and of course, block copolymers

can differ markedly with respect to their interactions with other homo- or

copolymers and thereby greatly affect miscibility behavior. This phenomena has

I been studied theoretically and in appropriate model systems and predictions of

3 effects have been made. In a parallel effort, extensive use has been made of

Monte Carlo lattice simulation technologies to investigate miscibility in a range of

I systems and under a variety of conditions. These studies have shed considerable

3 light also on interfacial and surface properties of blends, (35, 44, 52, 79, 82).

5. NOVEL MACROMOLECULAR ARCHITECTURE AND

CHARACTERIZATION

3 Certain studies in this thrust have overlapped other thrust efforts and in

some cases have therefore already been discussed. Highlights include the novel

electron microscopic morphological investigations of Prof. Thomas (Appendix 3),

1 (47, 48, 95, 96, 97) and the dynamic light scattering studies of solvated

macromolecules in constricted geometries. In a series of investigations the

translational diffusion of polymers in the channels of controlled pore glasses have

I been measured for the first time as function of macroscopic architecture and other

3 parameters (11, 61, 77, 78, 85, 101). Also new solid state NMR techniques have

been employed to investigate the microstructures of polymer blends, (34, 39, 60,

U 92).

I1

3 13

This thrust has revolved around the developments in novel high

I temperature polymer blends carried out at FMI and is described extensively in

SI Appendix 1.

IIIII-iIiIIUIIIU

I

3 APPENDIX 1

3 FOSTER MILLER INC.

IU

PROCESSING AND PROPERTIES OF ULTRAHIGH3 PERFORMANCE POLYMER BLENDS

I Submitted by:Kent G. Blizard

Tom FuscoMark A. Druy

I

II[IIII

I

I

lI Processing and Properties of Ultrahigh Performance Polymer Blends

3 This report summarizes three years of effort devoted to processing of polymer blends undersubcontract to the University of Massachusetts.I

During the first year of the program, we investigated the processing, rheology, and thermal-

mechanical behavior of polyimide PZ)/polyethersulfone (PES) blends. By blending the polvimideas the major component with PES under the proper conditions, the resulting blend was melt3 processible and optically translucent, while retaining outstanding thermal and mechanical

properties. The polyimide (Ciba Geigy Matrimid 5218) by itself is not processible in the melt3 state, necessitating solution casting methods to obtain film. Because of the processing cost and

environmental concerns, ultrahigh performance polymers suhc as Matrimid, to be of commercial3 interest, must be processable using standard melt processing equipment.

Specific accomplishments in processing and characterization studies of PI/PES melt blends

I include the following:

3 Melt blending PES with PI with 50 to 80% PI in a Brabender torque rheometer

resulted in a homogeneous, translucent blend similar to those obtained by

3 coprecipitation from a mutual solvent

0 Melt mixing studies on the Brabender were scaled up to the 25 mm Berstorff

twin screw extruder

3 The 67/33 PE/PES blend was melt processed with the twin screw extruder into

rods and pellets. This scale up required an interactive optimization of the3 screw configuration and processing temperatures since the processing window

is relatively narrow.

I Both the 67/33 and 80/20 blends wer compression molded into films and

sheets.

* Initial blend characterization studies indicated use temperatures of these blends

in the range of 250'C to 300°C depending on composition.

IU

While melt blending Matrimid with PES does not appear to give a molecularly miscible

blend, this system retains the exceptional thermal and mechanical properties of the polyimide,

along with optical translucency usually associated with molecularly miscible blends.

During the second year of this effort, we explored other polymer systems in a similar effortas in the first year. The second year's effort focused on the processing, rheology, and

thermomechanical behavior of thermoplastic polyimide (TPI)/polyetherimide (PEI) blends. By

blending the polyimide as a major component with this amorphous engineering resin, most of the

outstanding thermo-mechanical properties of the polyimide were retained while substantially

lowering the cost of the blend.

The thermoplastic polyimide (Aurum 450C of Mitsui Toatsu), while processable in the melt

state, has the drawbacks of a semicrystalline material in composites manufacture and a price

comparable to exotic materials such as Kapton. Films of TPI, PEI (Ultem 6000), and blends of

these materials having 50 and 80 percent by weight of TPI were produced. These films were

yellowish in color, but were transparent. Thermal analysis (DSC and DMTA) showed a single

glass transition temperature (Tg) which increased from 227"C to 252"C with increasing TPI

content. The tensile properties of the films were similar to those reported by the vendors, with

0.32 Mpsi modulus, 12 kpsi tensile strength, and 30-60% elongation at break depending on

composition. The alloys showed no unexpected trends either in solid or melt behavior.

Significantly, unlike the TPI itself which showed 15% crystallinity on annealing, the blends alloys

remained largely amorphous, with only 0.5% and 2.1% crystallinity, respectively, for the alloys

containing 50 and 80% TPI. In addition, a 4-6"C melt point depression was observed in the TPI

crystalline phase when blended with PEI. The second year's effort resulted in the following

conclusions:

" Blends of Aurum 450X. -v ith Ultem 6000 are miscible over the composition

range studied (up to 50% Ultem).

0 Crystallization is inhibited in the 80/20 TPI/PEI blend and virtually absent inthe 50/50 blend. The semicrystalline TPI is largely incorporated into the

amorphous alloy phase.

"* DMTA corroborated the DSC evidence of a shift in 'g with composition,

which monotonically increased-'* - inceasing TPI content.

II Melt flow behavior of the blends closely resembles that of both components,

with an onset of shear thinning at about 10 s-1. Viscosities observed in the3 RMS were in relatively good agreement with those seen using the Brabender

torque rheometer.

1 Static tensile measurements were only slightly less than those reported by thevendors, and could be due to measurement differences. Lower transverse

direction ultimate properties are likely due to film flaws since the TD modulus

is not affected.

In the third and final year of the program the TPI/PEI blends were incorporated as matrices

in carbon fiber composites and tested for mechanical behavior and physical attributes such as resin

and void content. A summary of the test results on films and composites are shown in Table 1.

- The superior electrical properties of the thermoplastic polyimide were retained in the blends.Increasing the TPI content did improve the high frequency and high temperature properties.I Adhesion to copper foil, extremely poor in the TPI because of crystallization, was improved to the

target value by alloying with 20% PEI, and to 13 pounds/linear inch (PLI) for the 50/50 blend.

Composite properties were good, but the composition of the matrix had little effect on the

resulting composite. Void contents were quite low, 2% or less, but because of little resin bleedout,

the fiber content was less than 50% rather than the target of 60%. The molding cycle was partially

optimized, but factors such as resin film thickness and molding time still need to be further

investigated.

Two important application areas for these blends have been identified: high performance3 electronics packaging, replacing such materials as Kapton, and a matrix resin for high temperature

composites.

UIIII

II

Table 1. Summary of Polyimide Blend Results AchievedITPI/PEI Blend NeTPI

E3 Tensile Modulus Mpsi 0.32 0.33

Tensile Strength, kpsi 12.0 13.0

I 250C Dielectric Constant (1 MHz) 3.2 3.2

I 2500C Dielectric Constant (1 MHz) 3.1 3.2

1 250C Dissipation Factor (1 MHz) 0.01 0.01

2500C Dissipation Factor (1 MHz) 0.02 0.02

Adhesion to Copper, pounds/linear inch 13.0 <4.0

IFiber Content, % 48.0 47.0

Void Content, % 2.0 -0.0

In-plane Shear Modulus, Mpsi 1.1 1.3

3 In-plane Shear Strength, kpsi 30.0 28.0

Publications:

Rheology and Mechanical Properties of Ultrahigh Performance Polyimide Melt Blends, K. G.I Blizard, M. A. Druy, and F. E. Karasz ANTEC '92 p. 585, (1992)

II

I

iIII

I FILMS AND COMPOSITES PRODUCED FROM

POLYIMIDE MELT BLENDS

[I[

I SUMMARY

Two important applicati-i areas for these blends have been identified: high

performance electronics packaging, replacing such materials as Kapton, and a matrix

I resin for high temperature composites.

By blending the thermoplastic polyimide as a major component with PEI under

I the proper conditions, most of the outstanding thermo-mechanical properties of the

I TPI were retained while substantially lowering the cost of the blend. The resulting

blend films have been incorporated as matrices in carbon fiber composites and tested

for mechanical behavior and physical attributes such as resin and void content. In

addition, electrical properties of the films were measured and compared to the neat

resins and lamination cycles to copper foil were established. A summary of the test

results on films and composites is shown in Table 1.

The superior electrical properties of the thermoplastic polyimide were retained

in the blends. Increasing the TPI content did improve the high frequency and high

temperature properties. Adhesion to copper foil, extremely poor in the TPI because

of crystallization, was improved to the target value by allowing with 20% PEi, and

to 13 pounds/linear inch (PLI) for the 50/50 blend.

I mmmmmmm m ~ u •m I

Table 1. Summary of Polyimide Blend Results Achieved

TIdj.P..I,.len Neat TPI

Tensile Modulus, Mpsi 0.32 0.33Tensile Strength, kpsi 12 13250 C Dielectric Constant (1 MHz) 3.2 3.2250* C Dielectric Constant (1 MHz) 3.1 3.2250 C Dissipation Factor (1 MHz) 0.01 0.01250* C Dissipation Factor (1 MHz) 0.02 0.02Adhesion to Copper, pounds/linear inch 13 < 4

Composite

Fiber Content, % 48 47Void Content, % 2.0 = 0In-plane Shear Modulus, Mpsi 1.1 1.3In-plane Shear Strength, kpsi 30 28

Composite properties were good, but the composition of the matrix had little effect

on the resulting composite. Void contents were quite low, 2% or less, but because of little

resin bleedout, the fiber content was less than 50% rather than the target of 60%. The

molding cycle was partially optimized, but factors such as resin film thickness and molding

time still need to be further investigated.

3

EXPERIMENTAL

Film Production and Testing

This past year's effort has greatly advanced the melt processing technology for these

blends. The thermoplastic polyimide (Aurum 450C of Mitsui Toatsu), while processable in

the melt state, has the drawbacks of a semicrystalline material in composites manufacture

and a price comparable to exotic materials such as Kapton. To overcome these limitations,

blends of TPI with PEI having 50 and 80 percent by weight of TPI were produced. The

details are presented as Appendix A. Thermal analysis (DSC and DMTA) showed a single

glass transition temperature (T.) which increased from 2270 C to 2520 C with increasing TPI

content. The tensile properties of the films were similar to those reported by the vendors,

with 0.32 Mpsi modulus, 12 kpsi tensile strength, and 30-60% elongation at break, depending

on composition. The alloys showed no unexpected trends either in solid or melt behavior.

Significantly, unlike the TPI itself which showed 15% crystallinity on annealing, the blends

alloys remained largely amorphous. with only 0.5% and 2.1% crystallinity, respectively, for

the alloys containing 50 and 80% TPI.

Electrical testing was performed on extruded films. The dielectric constant of

polymer films was measured by forming a capacitor from the material and measuring its

performance effects on an AC electricai circuit. The parallel-plate capacitor was formed

by sputtering a circular metal film (either gold or silver) of a known size (38 mm in

diameter) onto both sides of the film. Gold lead wires were used to connect this capacitor

to an HP 4284A LCR meter, which is capable of measuring all components of electrical

impedance at any set of frequencies from 20 Hz to 1MHz.

Films of each composition were laminated to a JTCS 1 oz. copper foil. The cycle

shown in Fig. 1 was used, although no optimization was performed.

4

Composites Manufacture and Testing

The initial molding conditions for the trial composites were based on DSC curves,

extrusion processing conditions and FMI composites manufacturing technology. The mold

used for both the trial and test laminate fabrication was designed by Foster-Miller to allow

hand layup of the composite along with a means to clamp and hold the fibers in place

during the compression molding cycle. All compression molding was done using a

programmable Tetrahedron press equipped with multi-stage temperature and pressure

ramping capabilities,

A two stage molding procedure was adopted, both for the trial and for the

subsequent test composites. A 6" x 6", four ply composite of [0,90,90,0] configuration was

fabricated and processed as a trial sample. Each of the four plies consisted of 24 tows of

fiber across, with a 2 mil thick film layer of 80/20 TPI/PEI blend between each ply. The

fiber used in the manufacture of the composites was 12k T650/35 Thornel carbon fiber

(Amoco). This layup was designed to yield a composite of 60% fiber by volume.

The initial molding conditions are shown in the mold cycle diagram in Fig. 2. All

steps were done under vacuum. These molding cycle parameters were sufficient to 'prepreg"

the material to a point at which the composite was consolidated enough to handle, cut and

remold during the optimization stage of the molding cycle. The original 6" x 6" composite

was cut into nine 2" x 2" squares. Four sets of two each were taken and remolded at four

different sets of conditions following the same type of cycle above. The four sets of

conditions were as follows (no vacuum):

0 150 psi at 400°C* 200 psi at 400( C* 200 psi at 410* C* 300 psi at 410*C

A 0.25" square sample was cut from each of the trial composites, along with a piece

from the original prepregged material. Each sample was potted in clear epoxy. The epoxy

was cured and the samples were ground down using different grades of fine sandpaper, 240

to 600 grit, and finally polished using a very fine diamond paste. A series of micrographs,

5

detailing the composites cross-section, were taken at 40X magnification. The micrographs

(not shown) revealed that the samples molded at 200 and 300 psi at 410' C were of good

quality. The dry fiber content was at a minimum while the consolidation was at a maximum.

However, it was found that at 300 psi, there was excess resin bleedout and fiber washout

that was not evident at 200 psi. Therefore, 200 psi at 410(C became the final molding

conditions of choice.

The fabrication of the actual test composites followed the same two step procedure

as for the trial composite. The prepregged material for each of the four film runs was two

sets of [0,90,90,0] plies and was 12.5" square. Once each of the prepregs was fabricated at

4000 C and 200 psi, a 6" x 6" piece was cut from the prepreg and remolded at the final

conditions of 200 psi at 4100C. This composite served as the source of the test samples.

A 24-ply composite of each material ("show" samples) was also made in the same fashion.

A number of 1/2" wide rectangular test samples were cut from each of the four eight-

ply test laminates at a 450 angle with respect to the composite's fiber orientation for in-

plane shear testing. These specimens were tabbed with 3/16" E-glass at each end. The

tabbed area on each specimen, along with the back of the tab, was lightly abraded using 240

grit sandpaper. The abrasion allowed a mechanical lock when the adhesive was added. A

thin film, epoxy adhesive was used to bond the tabs to the samples. All the tabbed

specimens were tested in tension. The testing was performed on a United Tensile Tester

equipped with a Sintech data acquisition system. The in-plane shear modulus and strength

determinations were carried out separately. The modulus was measured with a MTS clip-on

extensometer using a 2.0" gauge length. The sample was allowed to loaa to 40% of its

expected breaking strength, at a speed of 0.05 in/min, to allow a best fit line to be drawn

and a modulus value to be calculated. After the modulus testing was completed, the MTS

extensometer was removed and the samples were tested to failure. Approximately three out

of every four test specimens failed in the gage area. The few samples that failed in the

tabbed area, had the failing point start at the tab and extend into the tabbed area. These

samples were noted, but were included in the results since they were within one standard

deviation of the excluded mean.

6

II

RESULTS AND DISCUSSION

Polyimide Blends for Electrical Packaging

In the electronics packaging field, polyimide films such as Kapton have found

dominance in certain high performance niche applications. However, these materials. are

expensive, hygroscopic, and hazardous to process. There is a clear demand for a film having

good thermal stability coupled with lower material and processing costs. Thermoplastic

polyimide blends have all these potential advantages. By combining Aurum semicrystalline

TPI with Ultem polyetherimide, a ductile amorphous copolymer, a miscible alloy is formed

I (see Appendix A). At a cost of several degrees in T., a film is produced with superior peel

strengths to copper as well as excellent electrical properties. These findings are discussed

in the following paragraphs.

The frequency dependence of the electrical properties of TPI/PEI blend films are

shown in Figs. 3 and 4. The dielectric constant at room temperature (Fig. 3) is seen to be

nearly identical to the TPI for blends containing 50 and 80% TPI. The dielectric constant

was a slightly decreasing function of frequency from 1 kHz to 1 MHz. However, for the

50/50 blend and neat Ultem, the dielectric constant increases significantly at frequencies

above about 400 kHz. The dissipation factor, shown in Fig. 4, remained below 0.01 for all

blend compositions until the frequency approached 1 MHz. Both the blends and neat

polyimides exhibited similar frequency response.

The temperature dependence of the electrical properties of TPI/PEI blend films

are shown in Figs. 5 and 6. The dielectric constant decreases slightly from about 3.2 to 3.1

with increasing temperature from room temperature to 250* C for all polyimide films. Films

containing Ultem PEI, however, show an increase in dielectric constant at 3000 C that is

I proportional to the amount of PEI in the alloy, seen in Fig. 5. Dissipation factor is

essentially the same for all blends, as shown in Fig. 6.

I For use as dielectric layers, polymeric films should have at least 6 pounds/linear inch

I7I

I

I (PLI) adhesion to copper foil. Ideally, this adhesion should be attainable thermally, i.e.,

without the use of adhesives which can detract from the performance of the board. This

I adhesion should also be achieved without sacrificing the ductility of the substrate

(particularly for tape automated bonding and flex circuitry) as is often the case if the

polymer crystallizes.

The use of Aurum by itself was limited by its crystallization behavior during

lamination to copper foil. The result was an extremely brittle laminate that is prone to

cracking. By alloying the TPI with Ultem, however, the crystallization was greatly reduced

or eliminated, greatly improving the adhesion of the film to copper. These results are

shown in Fig. 7 in which the peel strength is plotted as a function of the percent of Ultem

in the blend. The target value was achieved with only 20% Ultem PEI, and with 50% PEI,peel strengths of 13 PLI, more than twice the target, were achieved. This performance

advantage came while maintaining most of the TPI's thermal stability and superior high

frequency dielectric properties.

Polyimide Blends as Composite Matrices

From the mechanical data obtained it was found that statistically there was little

difference between the four composites with different resin formulations, as summarized in

Table 2. Although the composite fabricated with neat Aurum 450C had the highest average

in-plane shear strength and modulus, the standard deviation was high enough that these

results overlapped with those from the other three composites. It was also apparent that

the mechanical data for the composites were partially fiber-based, evidenced by in-plane

shear strength and modulus values 2 to 3 times that of the film itself. Thus, it is possible

that any or all of the mechanical results could be skewed depending on precisely what angle

the test samples were cut. With the 3 or 4' tolerance in machining, it is very possible that

two sets of specimens could be several degrees apart from each other relative to the fiber

3 direction in each of the composites. The test results, beyond showing reasonable fiber-

matrix adhesion, should be interpreted with caution.

*8

I

I3

Table 2. Composite In-plane Shear Results

3 Matrix Resin Strength ModulusT PEL si Mpsi

I 100/0 27.8 ±-1.2 1.28 ±-0.2480/20 29.6 ±-1.6 1.01 +0.1650/50 26.9 + 1.2 1.05 ±.0.060/100 22.9 +2.0 1.09 ±0.07

I Samples of the composites made with neat Aurum 450C and the 50/50 blend were

tested for fiber and void volume percentage by means of nitric acid digestion at 660C

according to ASTM D-3171. The results are summarized in Table 3. No difference was

3 seen between the Aurum matrix resin and the 50/50 alloy.

3 Table 3. Composite Composition by Acid Digestion and Optical Microscopy

I Matrix Resin Fiber Volume % Resin Volume % Void %

TPI/PEI Acid OM Acid OM Acid

100/0 47 39 53 61 _3 80/20 - 49 - 51 -

50/50 48 45 52 55 2.0

0/100 - 40 - 60 -

IA series of optical micrographs of a sample from each of the test laminates was

j taken. The samples were prepared as discussed earlier. The micrographs were taken not

only to check the laminate quality, but also to visually confirm the fiber volume testing. The

micrographs from each composite are shown in Fig. 8. In general the fiber wet out was very

*9

I

I

3 good with minimum voids (black regions in the photos). However, visually the fiber volume

looked somewhat low. This observation was confirmed by a fiber count of each composite

£ specimen, the results of which are also shown in Table 3. In agreement with the acid

digestion findings, the fiber content was only 39 to 49% rather than the 55 to 60% desired.

The most likely cause of low fiber content was the use of 2 mil thick film plies. The

relatively high viscosity of these alloys (see the appendix) resulted in only minimal resin

bleedout. By utilizing - 1.5 mil film for the layup, an amount of resin closer to the

theoretical requirements for a 60 vol% fiber content composite should result in less

pronounced resin rich regions.

1IIIUIiII|I

I

II

i ACKNOWLEDGMENTS

Work at Foster-Miller was performed under a subcontract to the University of

I Massachusetts through, Force grant AFOSR-90-0150. We would like to acknowledge the

! able assistance of John Larouco and Barry Treadway in characterizing the blends.

[

IIIII

II

I

I

Ii£

300 350* Si I I I

*II I IIIi I I3 t I I

250 - - 300--- --- -- --- --- I - -, .....--.. . 2 5 0 ._

200

150

-- -- -- -- -I ---- -- -. --------- ---- ---.. .- - --- 1 5 0

I 0 : 0

0 10 20 30 40 50 60 70

STime, minutes

UI

Figure 1. Lamination Cycle for Copper / Polyimide / Copper

1!1

III

IIII

* 450 1503I ,I II

'CL

II

3 7 5 -------.. . .. .. . .. .-- ------ ------ --.-- --- --- ..-- -12I

0 i i i I

'I iI I

0 10 20 30 40 50 60 70 80 90 100

I Time, minutes

I

Figure 2. Initial Molding Cycle for Polyimide / Carbon Fiber Composites

* 13

..I ..., ,,_. .., ..., ...,, ,, o

IIII

1 3.4 Percent Ultem

I ,_

20

3.3 _- -v_--__,_

\c_ _ _ _ _

v.- -- 7 - -

41U•: 3 .2 -

0

00) 50 0

14.100

3.0 25.C

2.9 3 104 105 10' 107

I Frequency, Hz

SI Figure 3. Frequency Dependence of Dielectric Constant

14

I

3

I

10 Percent Ultem

0~~

0~o 50-02 0

1. 100 V i

5-25C

10...............I.................I......................., ,,,

1000

103 104 105 log 107

Frequency, Hz

Figure 4. Frequency Dependence of Dissipation Factor

I is

I!

S~3.4

50/50 TPI/PEI

3.3 . .S= " ,TPI

00

S• 3.2 - . ...- b. -

-O 0:

*0 03.1- • a ~~~................ m 0 2 P / E - ' /

~3.0 o.80/20 TPI/:EI- _• 3.0 .

OI1 [] , . ...... * - . "3

2.9

2.8 1 MHz PEI

-2.8 I I I

0 50 100 150 200 250 300

Temperature, C

i

IFigure 5. Temperature Dependence of Dielectric Constant

Sx16

I

i 0.051 MHz 50/50 TPI/PEI

0.04* am

IL. 0.03 PEI .,*

0.02 80/20 TPI/PEI .,;E ,A /

0 .0 ...... .. 80.0 - •.. . - - • , ._: . ' . -

0.00 I ,

0 50 100 150 200 250 300

Temperature, C

Figure 6. Temperature Dependence of Dissipation Factor

17

I

15

12 - Ile

"a-

01

Percet Ulem inAurue

i

Figure 7. Peel Strength of Polyimide Melt Blends

18

Q -. 0

-it,

r~7 -- 7.

-- V J

_

V a,

Aq

ý

* -~ I - - ~~row

APPENDIX 2

WRIGHT STATE UNIVERSITY

Submitted by W.A. Feld, P.I.

J. J. Kane, Co. P.I.

U3 Table of Contents

U I. A Facile Synthesis of 3,4-Dialkoxythiophenes.

II. Synthesis of a Series of Thiophene Containing Schiff Base Polymers and

3 Model Compounds

SIII. Evaluation of Second Order Polarizability (03) Using Solvatochromism.

1 IV. Synthesis and Evaluation of Second O)rder Polarizabilities of Novel

3 Benzimidazoles using Solvatochromism.

I V. Synthesis of Poly(aryl ether N-substituted benzimidazoles) by Nucleophilic

Aromatic Substitution.

3 VI. Synthesis of a Series of Conjugated Enyne Polythiophenes

SVII. Synthesis of a Series of Conjugated Enyne Polythiophenes, II.

VIII. The Synthesis of Alternating Poly(heterocycles): Poly(3,4-Didecyloxythiophene-alt-thiophene and Poly(3,4-Didecyloxythiophene-alt-5 (N-phenylpyrrole))

IIU|

!2

I~L A Facile Synthesis of 3,4-Dialkoxythiophenes.

Alkylation of diethyl 3,4-dihydroxy-2,5 -thiophenedicarboxylate with dimethyl sulfate, I -

I ~bromobutane, 1-bromodecane, 1,2-dibromoethane, 1,3-dibroniopropane, or benzyl chloride with

I potassium carbonate in DMF yielded diethyl 3,4-dimethoxy-2,5-thiophenedicarboxylate, diethyl

3,4-dibutoxy-2,5-thiophenedicarboxylate, diethyl 3,4-didecyloxy-2,5-thiophenedicarboxylate,

I diethyl 3,4-ethylenedioxy-2,5-thiophenedicarboxylate, diethyl 3.4-propylenedioxy-2,5-

thiophenedicarboxylate and diethyl 3,4-dibenzyloxy-2,5-thiophenedicarboxylate, respectively.

IHO OH R20 ORI

C2H5 0 /' OC2H5 + RX 1W C03 0S CH

YDM F, 1 O0 CS

0 0 0 0

RX = CH3OS(O) 20CH3 R 1, R2 = -CR3IRX = Br-C4Hg R1, R2 = CHRX = Br-CH 10CH21 R 1, R2 = -CH IOCH2 1RX = Br-CH2CH2 -Br R 1, R2 = -CH2CH2 -RX = Br-CH2CH2CH 2-Br R1, R2 = -CH2CH2CH2-RX = Cl-CH2C6H5 R 1, R2 = -CH2C6 H-5

I Hydrolysis of these dialkoxy compounds yielded 3,4-dimethoxy-2,5-thiophenedicarboxylic

U acid, 3,4-dibutoxy-2,5-thiophenedicarboxylic acid, 3,4-didecyloxy-2-5-thiophenedicarboxylic

acid, 3,4-ethylenedioxy-2,5-thiophenedicarboxylic acid, 3,4-propylenedioxy-2,5-

I thiophenedicarboxylic acid and 3,4-dibenzyloxy-2,5-thiophenedicarboxylic acid, respectively.

Decarboxylation of the diacids yielded 3,4-dimethoxythiophene, 3,4-dibutoxythiophene, 3,4-

I didecyloxythiophene, 3,4-ethylenedioxythiophene, 3.4-propylen,-dioxythiophene, and 3,4-

dibenzyloxythiophene, respectively. The yields for these reactions were good and the products

I ~were distilled or recrystallized. Some of the diallcoxytbiophenes were unstable and decomposed

I upon standing. In addition, reaction of 3,4-didecyloxy-2,5-thiophenedicarboxylic acid with

mercuric acetate and iodine and with thionyl chloride yielded 3,4-didecyloxy-2,5-

I diiodothiophene and 3,4-didecyloxy-2,5-thiophenedicarbonyl chloride, respectively. Reaction of

3

3,4-didecyloxy-2,5-tbiophenedicarbonyl chloride with ammonium hydroxyde yielded 3,4-

didecyloxy-2,5-thiophenedicarboxamide. 1 O

3R 20 OR1 H20, CH30H R20 ORI

3C 2H50 0C2H5 2.KHHO OH

3 RI, R2 = -CH3RI, R2 = -C4HgRj, R2 = -CHIoCH2lRI, R2 = -CH2CH2 -3 RI, R2 = -CH2CH2CH2R 1, R2 = -CH2C6 H5

IR 10 OR2 R10 OR2Cu0 IA5HO OHDo/ \or Meft

0 0

RI, R2 = -C4H 9Ri1, R2 = -CH IOCH 21

Rj, R2 = -CH2C6 H5

IR 10 OR2 R10 OR2

HO ' OH Cu0 Ouinoline

0 0

RI, R2 = -CH3R 1,R2 = -CH2 CH2 -

R 1, R2 = -CH2 CH2 CH2-

4

UH 21C100 0ClOH21 H21C100 CIH2HOAc

*HO OH + Hg(OAC)2 10-C)g /S H(~;

0 00

3H 21CI00 0010H21

H21C100 0ClOH21 +H 21CI00 OClOH21

HO OH + SC2CACS

0 0 0 0

NH3

H21C100 0ClOH21

H2N NH2

* 00

3 IH. Synthesis of a Series of Thiophene Containing Schiff Base Polymers and ModelCompounds

5 Four new poly(Schiff bases), poly[[3,4-bis(decyloxy)-2,5-thiophenediyl]methyl-

idynenitrilo-4, 1-phenylenethio- 1,4-phenylenenitrilomethylidyne], polytIS,2-pyridinediyl-

I ~thio-2,5-pyridinediylnitrilomethylidyne[3,4-bis(decyloxy)-2,5-thiophenediylllmethylidynenitrilol,

I poly[ [3,4-bis(decyloxy)-2,5-thiophenediyl]methylidynenitrilo- 1 ,3-phenylenenitrilomethylidyneI

and poly[[3,4-bis(decyloxy)-2,5-thiophenediyllmethylidynenitrilo- 1,4-phenylenenitrilo-

U methylidyne] were synthesized by the condensation of 3,4-didecyloxythiophene-2,5-di-

carboxaldehyde with 4,4'-diaminodiphenyl sulfide, 5,5'-diamino-2,2'-dipyridyl sulfide,

5

3 m-phenylenediamine, and p-phenylenediamine, respectively. With the exception of

I poly[ [3,4-bis(decyloxy)-2,5-thiophenediylllmethvlidvne nitrilo -I1 3-phenylenenitrilomethylidyriel,

the polymers were soluble in methylene chloride, NN-dimethylformnamidde, N,N-dimethyl-

I acetamide, and tetrahydrofuran. Poly[[3,4-bis(decyloxy)-2,5-thiophenediyljmethylidyne-

nitrilo- 1 ,3-phenylenenitfilomethylidynel was soluble in methanesulfonic acid.

1) Poly[ [3,4-bis(decyloxy)-2,5-thiophenediyllmethylidynenitrilo-4, I1-phenylene -U ~thio- 1 ,4-phenylenenitrilomethylidyneI

H2 1CIO 0 0H2

oxy)-2,5-thiophenediyl]miethylidynenitfiloJ

IH 21C1 00OlO2

I~ £Ii~CH=N \/S /N=CH4-

3) Poly[ [3,4-bis(decyloxy)-2,5-thiophenediyllmethylidynenitrio- 1 ,3-phenylene-nitrilomethylidyne]

H21 C1 0 0 0ClOH21

S CH=N N=CHtn

4) Poly[113,4-bis(decyloxy)-2,5thiophenediyl]methylidynenitrilo-1I,4-phenylene-U ~nitrilomethylidyne]

H2 1C10 0 0ClOH21

S ZCH=N - /N=CHin

6

3 Two new model compounds, N-[[3,4-bis(decyloxy)-2,5-thienyllmethyl-

ene -N',N'-dimethy1- 1,4-benzenediarniine and N-[[3,4-bis(decyloxy)-2,5-thienyl]-

I methylene]-3-aminopyridine, were also synthesized by the condensation of 3,4-didecyl-

oxythiophene-2,5-dicarboxaldehyde with N,N-dimethyl- 1,4-phenylenediaxn-ine and

3-aminopyridine respectively.

31) N-[[3,4-bis(decyloxy)-2,5-thienyllmethylene)-N',N'-dimethyl- 1,-ezndaie

IH 21CI 00 0ClOH21

H3 C, -Z \ ,/CH3IH 3C--*N-ONC / CH=N-< /N.

2) N-[[3,4-bis(decyloxy)-2,5-thienyllmethylenel-3-amiinopyridine

H2 1C10 0 0ClOH21

N -4=HCZS$CH=N " N

\ / / N

methyl- 14-benzenediamine was also prepared as a precursor for the future synthesis of donor-

acceptor model compound.

I-[,-i~eyoy--[4ntohniinnlehl--heylehlene -N',N'-dimethyl- 1,4-benzenediamine

H2 1CI 00 0ClOH2 1

0NN=HCiS CH=N N ,CH 3

7

I

SH2 1C I0O • O_• loH 21 +- N CH 3

OHC>•%S> CHO + NH2 e- -- NI Room temp, 1/2 h

I H 2 1CIoO OCloH21

H3C\ -z :

\3-o / -N=CH S CHO

i I. Evaluation of Second Order Polarizability (13) Using Solvatochromism.

The second order polarizabilities (13) of five organic compounds were evaluated using

solvatochromism. Solvatochromism uses a two level approximation in the determination of 13.

According to the two level approximation, 13 depends only on ground state and first excited state

I dipole moment. Solvatochromism can measure the change in dipole moment resulting from the

transition.

Five compounds were analyzed for their NLO activity, p-nitroaniline (I), N, N dimethyl-p-

E nitroaniline (I), 1,6-diphenyl-2- [4(N, N-dimethylamino) phenyl ] -5- (4-nitrophenyl) benzo

(1,2-d;4,5-d') diimidazole (II), 1,4-diphenyl-2- [4(N, N-dimethylamino)phenyl] -5- (4-

I nitrophenyl) benzo (1,2-d;4,5-d) dilmidazole (IV), and N, N dimethyl-p-anilinopyrrole (V).

I RN.,R R"N/R

I I. R = H II. R = CH3 V

I8

I

II

I HACI NSH 3C 0

III Iv

I The two level model has been shown to be an easy way to evaluate P}. There are however

some limitations to this model. As it was shown by compounds III and IV, the two level model

could give suspect values. The two level model will only work for compounds that have exactly

one low-lying charge transfer excited state. If more than one excited state appears than the two

level model will be unusable. The evaluation of the parameter gg is also troublesome. Some of

I these types of compounds are hardly soluble in the standard solvent used which is usually non-

polar. If this is the case then the Pg will have a large uncertainty. For this work the solvent

availability was limited. It would be better for solvatochromic shift measurements to have more

solvents. The effect of temperature can also be reduced if the environment of the experiment can

be controlled. There is no doubt that temperature fluctuation reduces the accuracy of the results

I obtained.

I9

I

I

IV. Synthesis and Evaluation of Second Order Polarizabilities of Novel Benzimidazolesusing Solvatochromism.

I The reaction of 2-aminodiphenylamine with 4-nitrobenzoyl chloride alid 4-

(dimethylamino)benzoyl chloride provided N-(2-anilinophenyl)-4-nitrobenzamide and N-(2-

anilinophenyl)-4-(dimethylanmino)benzamide, respectively. The benzamides were thermally

dehydrated to 1-phenyl-2-(4-nitrophenyl)benzimidazole and 1-phenyl-2-[4-

(dimethylaminophenyl)]benzimidazole. The benzamides and benzimidazoles were characterized

I employing 1H NMR, 13 C NMR, IR, and elemental analysis. The second order polarizabilities

(3) were determined by a two-level model approximation using solvatochromism. The

parameters Peg (transition dipole moment), Oaeg (frequency of transition in the solvent), Jg

(ground state dipole moment), lie - Jig (difference in the excited and ground state dipole

moment), and ge (excited state dipole moment) used in the evaluation of 8, were determined

I experimentally. For 1-phenyl-2-(4-nitrophenyl)benzimidazole, Meg= 2.95 (106) m-1. Peg was

3.73 D, gg = 4.03 D, pe - jig = 2.39 D, Pe = 6.14 D, and B = 47.09 (10-30) esu at 1064 nm. For

1-phenyl-2-[4-(dimethylaminophenyl)]benzimidazole, weg = 3.06 (106)m- 1, Peg = 3.73 D, pg =

I 4.96 D, l±e - I±g = 1.39 D, g.e = 6.95 D, and 8 = 34.11 (10-30) esu at 1064 nm.

(C6H5 )HN

0 2 N 0- OCI + H2 N"-''b

I I THF,Pyridine

(C6H5)HN

I O~~2N-KO-CONH CIII

!1Ul

U

IC6 H5

I I2 (CH3)2 N 00 2N-0 C),(C6 H5 )HN

THF,S~ Pyridine

(CH30-0 CONH

Il C6H5

NH

0 AcOH,

(OH3)2 N-/ C-NJI Q A-. (CH*)N-O -Q

C6 H5

IV. Synthesis of Poly(aryl ether N-substituted benzimidazoles) by Nucleophilic Aromatic

Substitution.

3 Five new poly(aryl ether N-substituted benzimidazoles) were synthesized by nucleophilic

aromatic substitution in which the generation of an aryl ether linkage is the polymer forming

reaction. The new difluoro bisbenizimidazole monomer, 2,2-bis( I-phenyl-2-(4-fluoro-

phenyl)benzimidazole-5-yljhexafluoropropane, was prepared and polymerized with bisphenols in

N-methyl-2-pyrrolidone in the presence of K2CO3 to afford the new PBIs, poly[ 1-phenyl-2,5-

I11I

benzimnidazolediyl)[2,2,2-trifluoro- 1 -(trifluoromfethyl)ethylidene]( 1 -phenyl-5.2-

benzimidazolediyl)- 1 ,4-phenyleneoxy- 1 ,4-phenyleneoxy- I .4-phenylene], poly[lI -phenyl-2,5-

U ~ ~benzirnidazolediyl)[2,2,2-trifluoro-l1-(trifluoromethyl)ethyl- idene]( 1-phenyl-5,2-

benzimidazolediyl)- 1 ,4-phenyleneoxy- 1 ,3-phenyleneoxy- 1 ,4-phenylenel, poly[lI -phenyl-2,5-

benzimiidazolediyl)[2,2,2-trifluoro- 1 -(trifluoromiethyl)ethylideneJ (1 -phenyl-5,2-

I ~ ~benzimidazolediyl)-1I 4-phenyleneoxy-1I,4-phenylene[12 ,2,2-trifluoro- 1-

(trifluoromethyl)ethylidenej-1I,4-phenyleneoxy- 1 A -phenylenel, poly[I1-phen-

I ~yl-2,5-benzimidazolediyl)[2,2,2-trifluoro- I-(trifluoromethyl)ethylidenej(1 -phen-

I ~~yl-5,2-benzimidazolediyl)- 1,4-phenyleneoxy- 1,4-phenyleneisopropylidene- 1,4-phenyleneoxy-

1 ,4-phenylene], poly[ 1 -phenyl-2,5-benzimidazolediyl)[2,2,2-trifluoro- 1 -(triflu-

I ~~oromethyl)ethylidenel( 1-phenyl-5,2-benzimidazolediyl)- 1,4-phenyleneoxy- 1,4-phenyl-

enesulfonyl- 1,4-phenyleneoxy- 1,4-phenylenel. The polymers exhibited excellent thermal

I stability up to 5000 C, and showed good solubility in common organic solvents. This synthetic

method is found to be a convenient and effective synthetic approach to poly(aryl ether N-

I substituted benzimiddazoles).

L Ph P'h

I ~Poly[tI(-phenyl-2,5-benzimidazolediyl)[2,2,2-trifluoro- 1-(trifluoromethyl)ethylidene](1I-phenyl-5,2-benzimidazolediyl)-1 ,4-phenyleneoxy- 1 3-phenyleneoxy- 1,4-phenyleneJ

F3C C

Ph Ph

Polyff(1-phenyl-2,5-benzimidazolediyl)[2,2,2-trifluoro- 1-(trifluoromethyl)ethylidene]( 1-phenyl-5,2-benzimidazolediyl)-1 ,4-phenyleneoxy- 1 ,4-phenyleneoxy- 1 ,4-phenylenel

12

I3 CF N 0

Poly[( 1 pheny1-2,5-benzimidazolediyl)[2,2,2-trifluoro- I1-I ~(trifluoromethyl)ethylidenel( 1-phenyl-5,2-benzimiidazolediyl)-1 ,4-phenyleneoxy- 1 ,4-phenylenesuifonyl- 1 ,4-phenyleneoxy-1 ,4-phenylenel

C F3Ph Ph

Poly[(1 -phenyl-2,5-benzimidazolediyl)[2,2,2-trifluoro- 1-I ~(trifluoromethyl)ethylidenel( 1-phenyl-5,2-benzimidazolediyl)-1 ,4-phenyleneoxy- 1 ,4-phenylene[2,2,2-trifluoro- 1 -(trifluoromethyl)ethylidene]- 1 ,4-phenyleneoxy- 1 ,4-phenylene]

Ph Ph

PolyjI(1 -phenyl-2,5-benzimidazolediyi)[2,2,2-trifluoro- 1 -(trifluoromethyl)ethylidenel( 1-phenyl-5,2-benzimidazolediyl)-1 ,4-phenyleneoxyl1,4-phenyleneisopropylidene- 1,4-phenyleneoxy- 1,4-phenylenel

I The new model compounds, l-phenyl-2-(4-fluorophenyl~benzimiidazole, 1-phenyl-2-(4-

phenoxyphenyl)beflzimfidazole, 1 -phenyl-2-[4-(3-methylphenoxy)phenyllbenzimidazole, 1,4-

bis[4-(1 -phenylbenzimidazole-2-yl)phenoxylbeflzene, 2,2-bis[I1-phenyl-2-(4-(3-

methylphenoxy)phenyl)benzimidazole-5-yllhexafluoropropane, were also prepared. MTR, I

nmr and 1Cnmr spectra of the model compounds and polymers are presented and discussed.

Thermal properties and viscosity data of the five new polymers were also determined

13

1 -phenyl-2-(4-fluorophenyl)bcnzimiidazole 1 -phenyl-2-(4-phenoxyphenyl)benzimidazolc

I 6 0H3

1 -phenyI-2-[I4-(3-methylphenoxy)pheflyI]bCJIzimidazoIC

IN

I 1 ,4-bis[4-(1-phenylbenzimiddazole-2-yl)phenoxylbenzene

I F3C CF3I / %

H3 CH3

I2,2-bis[ I -pey--4(-ehlhnx~hnlbniiaoe5yjealoorpn

14

IVI. Synthesis of a Series of Conjugated Enyne Polythiophenes

Our laboratories have been directing certain research efforts toward development of new

I materials possessing optimal third-order nonlinear optical (NLO) properties. This property is

primarily concerned with the response of a dielectric material to an intense beam of light. Thus

we are compiling a NLO model compound database in order to uncover third-order molecular

structure-NLO property relationships. These data will serve to further refine guidelines for

design of organic polymeric materials predicted to exhibit optimal properties in this regard.

I Previous reportsi have ebtablished that extended pi conjugation and heterocyclic groups such as

thiophenes are among the structural features which enhance third-order NLO responses.

The paper presents the synthesis of new series of conjugated polymers (and a representative

5 model compound) intended for evaluation of third-order NLO properties. The polymeric systems

have enyne and thiophene units in the polymer backbone. Also included as a structural feature

are decyloxy appendages at the 3,4 positions in the thiophene rings in an effort to overcome the

well known solubility limitations of conjugated polymers.

Synthesis of Model Compound and Polymers

3 A series of four (VI-IX) conjugated enyne polythiophenes were synthesized by palladium (HI)

catalyzed coupling 2 ,3 of 3,4-didecyloxy-2,5-bis(13-bromoethenyl)thiophene with an aromatic

diethynyl compound as shown in Scheme 1. The resulting polymers were all dark red and were

cast into thin films from THF. Once dried, none of the polymers would redissolve.

DSC scans of VI - IX are similar showing a single large exotherm with onset ranging from

300 to 3800 C. (Table 1) TGA scans indicated two-stage degradation with extrapolated onset

ranging from 281 to 3250 C followed by a second shoulder ranging from 496 to 5480 C (Table

I I ).

Solution viscosities were measured in THF at 30' C and extrapolated to zero concentration.

I Values ranged from 0.27 to 0.90 dL/g (Table 1).

II

15I

I

RO OR

+ HC-C-Ar-C-CH (O'P)YwI"I, CulASX (CH3CHz)NH/HFt

BrHC-CH"S"C H=CHBr

IVa: trans. transIVb: cistrans

RO OR

4C=C-CH=CH I CH=CH-C-C-Ar--h

U VI, VII. VIII. IX

I Polymer VI trans, trans A -

3 Polymer VII trans, trans Ar = RO- 0 R

Polymer VIII trans, trans Ar

Polymer IX mixture of trans, trans A -I and cis, transR _-OCH(CH),Q-, Scheme 1

3 Table 1

Thermal and Viscosity Data for Polymers VI - IX

DSC/onset TGA/onset TGA/2nd [n1

Polymer 0 C _ C 0 C dL/g

VI 300 281 496 0.32

VII 350 325 548 0.90

VIIIn 380 327 532 0.27

IX 350 328 534 0.74

1I

16I

IThe model compound trans, trans-3,4-didecyloxy-2,5-bis(4-phenylbut- l-en-3-yn- -yl)-

thiophene, V, was prepared by coupling IVa and ethynyl benzene as shown in Scheme 2. This

I compound decomposed on standing at room temperature.

3RO OR

SIVa +N , C---CH O,-C,--ClH--'CH " CH=CH-C-=CO

V(CHCHNH V Scheme 2

Synthesis of Monomers

I Monomer IV was prepared by a five-step sequence (Scheme 3) starting with diethyl-3,4-di-

I decyloxythiophene-2,5-dicarboxylate which was reduced to the diol, I, with LiAlH4. Oxidation

of I with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) gave dialdehyde, II. A Wittig4 type

£ reaction with tetrabromomethane converted II to bis-vinylidene bromide, III. Finally, III was

converted to 3,4-didecyloxy-2,5-bis(-bromoethenyl)thiophene, IV, by reduction with diethyl

£ phosphite5 to give a 60 percent yield of the trans, trans isomer, IVa and a 37 percent yield of the

cis, trans isomer.

RO OR RO OR

H3CHKCOC COS 2CH4CH, 70% HOJHC ý CH:OH 83%I I

RO OR 03 P, CBr4 RO OR (W&OI 0CHOC~r--('CH H=CBr,

CH2C12; 59 % Et3N

i II III

RO OR RO OR

H. )N H + H I \ Br

Br )- H Br Bi r 1 It H

SIVa, 60 % IVb, 37%

Scheme 3.

17I

I5 The diethynyl monomers 1,3- and 1,4-diethynylbenzene were made by modifications of

published6 ,7 methods. The synthesis of 1,4-diethynyl-2,5-didecyloxybenzene will be described in

I a later publication.

I REFERENCES

1. M. Zhao, M. Samoc, P. N. Prasad, B. A. Reinhardt, M. R. Unroe, M. Prazak, R. C. Evers,J. J. Kane, C. Jariwala and M. Sinsky, Chem. Mater. 1990, 2, 670.

2. K. Sonogashira, Y. Tohda and N. Hagihara, Tetrahedron Letters, 1975, 50, 4467.

3 3. B. A. Reinhardt and F. E. Arnold, U. S. Pat. No. 4,417,039 (Nov. 1983).

4. E. J. Corey and P. L. Fuchs, Tetrahedron Letters, 1972, 36, 3769.

5. T. Hirao, T. Masunaga, Y. Ohshiro and T. Agawa, J. Org. Chem., 1981, 46, 3745.

6. D. L. Trumbo and C. S. Marvel, J. Polym. Sci., Polym. Chem. Ed., 1986,24, 2311.

1 7. A. S. Hay, J. Org. Chem., 1960, 25. 637.

VIL Synthesis of a Series of Conjugated Enyne Polythiophenes, U.

Recently we reportedl the synthesis of a series of enyne polythiophenes based on structmre A.

This effort is part of our ongoing program to develop new materials possessing optimal third-IRO OR

i 3Rt~CE=C-CH=CHi7KH=CH-CFC-Ar}3 A

£ order non-linear optical (NLO) properties. This property is primarily concerned with the

response of a dielectric material to an intense beam of light. Thus, we are compiling an NLO

model compound database in order to uncover molecular structure-NLO property relationships.

3 These data will serve to further refine guidelines for design of organic polymeric materials

predicted to exhibit optimal NLO properties. Previous reports2 have established that extended pi

3 conjugation and heterocyclic groups such as thiophenes are among the structural features which

enhance third-order NLO responses.

18I

SThis paper presents the synthesis of a model compound and a series of four new enyne

polymersthree (VII, VIII, and IX) of which are isomers (see structure B) of series A and

RO OR

I +~~CH=CH CCI$CCCH=CH-Ar+

i bincorporate the enyne and the thiophene and benzenoid rings in the polymer backbone. The

I fourth polymer (X) incorporates the enyne and thiophene rings in the polymer backbone. The

effects of these structural variations in series A and B on NLO properties will be the subject of a

later publication.

I Synthesis of Model Compound and Polymers

A series of four (VII-X)) conjugated enyne polythiophenes were synthesized by palladium

I (H1) catalyzed coupling3,4 of 3,4-didecyloxy-2,5-diethynylthiophene, 1, with aromatic ois(f-

bromovinyl) monomers as shown in Scheme 1. The resulting polymers were obtained in

quantitative yields. They were orange in color and were cast into thin self-supporting films from

I THF. Once dried,the polymers did not redissolve.

Po" vly V am trans ---

aPolyme Vill ftrisftmai Ar - Ro Q OR

Po*me tris, tram

RO OR

jPdolmer X nftxeol ats ansra Ar-a

5 R - OC10H21 Scheme 1

i DSC scans of VII - X, like their isomers in Series A, showed a single large exotherm which

is attributable to decomposition when compared to the TGA scans. TGA data (Table I) showed

119I

Ithe characteristic two stage degradation with onset ranging from 255 to 328°C followed by a

second shoulder ranging from 386 to 520°C (in air).

RO OR(03 P)2 PdCI2 , Cul

I\+ BrCHC::H-Ar--CH=CHBr

H- H Et3 N, THF

IRO OR

-FCH=CH-C-C)EC=-~CC--CH=CH-Ar+I VII, VIII, IX, X

5 Solution viscosities were measured in THF at 300C and extrapolated to zero

concentration. The intrinsic viscosities ranged from 0.53 to 0.87 dL/g (Table I).

£ Table 1

Thermal and Viscosity Data for Polymers VII - XITGA/onset TGAi2nd [11]

3Polymer 0 C, (air) 0 C, (air) dL/g

VII 273 386 0.88

VIII 255 417 0.53

IX 280 483 0.72

X 328 520 0.60IThe model compound 3,4-didecyloxy-2,5-bis(4-phenyl-3-buten-1-ynyl)thiophene, II, was

prepared by coupling reaction of monomer I with P-bromostyrene. The low melting yellow

5 solid, unlike its isomer, 3,4-didecyloxy-2,5-bis(4-phenyl-1-buten-3-ynyl)thiophene, is stable at

room temperature.

II

20I

I

I H21C100 O 0H21

0-CH-CH-C--C " C_ C-CH CH-0

Monomer Synthesis

3 3,4-Didecyloxy-2,5-diethynylthiophene, I, was made by treatment 5 of

3,4-didecyloxy-2,5-bis(p, 0-dibromoethenyl)thiophene I with n-butyl lithium. This monomer was

quite unstable and had to be refrigerated and re-purified immediately before use. The trans,

I trans-1,4-bis(P-bromovinyl)benzene was made from 1,4-phenylenediacrylic acid by the method

of Mitchell and co-workers 6. The monomers trans,zrans-2,5-didecyloxy-l,4-bis(13-bromovinyl)-

benzene, IV, and trans, trans-1,3-bis(1-bromovinyl)benzene, VI, were made by conversion of the

corresponding dialdehydes to their respective bis(PP-dibromovinyl)benzene derivatives with

Icarbon tetrabromide and triphenyl phosphine followed by reduction with diethyl phosphiteI. The

i synthesis of 2,5-didecyloxy-1,4-benzodialdehyde (starting material for monomer IV) will be

described in a later publication.IREFERENCES

3 1. J. J. Kane, F. Gao, B. A. Reinhardt. and R. C. Evers, Polymer Preprints, 33, 1064

(1992).

2. M. Zhao, M. Samoc, P. N. Prasad, B. A. Reinhardt, M. R. Unroe, M. Prazak, R. C. Evers,

L J.J. Kane, C. Jariwala and M. Sinsky, Chem. Mater., 2, 670 (1990).

3. K. Sonogashira, Y. Tohda and N. Hagihara, Tetrahedron Letters, 50, 4467 (1975).

4. B. A. Reinhardt and F. E. Arnold, U. S. Pat. No. 4,417,039 (Nov., 1983).

5. E. J. Corey and P. L. Fuchs, Tetrahedron Letters, 36, 3769 (1972).

1 6. R. H. Mitchell, B. N. Ghose and M. E. Williams, Can. J. Chem., 55, 210 (1977).

2I

21I

IVIII. The Synthesis of Alternating Poly(heterocycles): Poly(3,4-Didecyloxythiophene-alt-

thiophene and Poly(3,4-Didecyloxythiophene-alt-(N-phenylpyrrole))

3 We have recently reported a versatile and improved route to 3,4-dialkoxythiophenes [I]. As

part of a project directed toward the synthesis of thiophene containing 2nd and 3rd order NLO

materials, we now report the use of 3,4-dialkoxythiophenes and related thiophene derivtives in

the preparation of alternating poly(heterocycles). These thiophene polymers are potential

I conducting materials when doped and are also potential NLO materials.

U Model Compound Synthesis

The aldehyde, 3,4-didecyloxy-2-thiophenecarboxaldehyde 2. can be prepared in excellent

yield from the corresponding 3,4-didecyloxythiophene 1. Bisformylation did not occur even

under pressing conditions and excess reagents. The application of the Corey-Fuchs procedure [21

to 2, yields 2-ethynyl-3,4-didecyloxythiophene 3, a relatively unstable material that was used

5 directly in a copper (1) catalyzed coupling reaction [3] to provide 1,4-bis(3,4-didecyloxy-2-

thienyl)butadiyne 4. Reaction of 4 with sodium sulfide nonahydrate [4] or aniline [3] provided

3 3,4,3",4"-tetradecyloxy-2,2':5'.2"-terthiophene and 2,5-bis(3,4 didecyloxy-2-thienyl)-N-phenylpyrrole

6. All new compounds were fully characterized as listed in the Experimental part.IR1:O OR RO OR 1)CBr4, Zn RO OR

DMF 2) BuU N3.1. 2 Hexane 3

CuCIPyridineTMEDA,

RO OR RO OR PhNH2 RO OR RO OR

Na2S.gHO S

JX-S, 6 X fNPh ,

22I

II Monomer and Polymer Synthesis

The synthesis of appropriate monomeric material involved the improvement of previously

reported synthetic step for the preparation of 3,4-didecyloxy-2,5-thiophenedicarboxaldehyde 1.

* The modified procedures, which are given in the Experimental section, consist of an improved

workup of a reported reduction and an MnO2 oxidation of a diol to the dialdehyde 2. The

I reaction of 1 under standard Corey-Fuchs conditions [3], yielded 3,4-didecyloxy-2,5-

diethynylthiophene . which could be transformed into 3,4-didecyloxy-2,5-bis(2-

trimethylsilylethynyl)thiophene 9, a more stable material than 8. A coupling reaction related

3 (2,6-lutidine was used as the solvent) to that used in the preparation of the butadiyne 4 was

employed as a polymerization reaction provide poly(3A-didecyloxythiophene-2.5-diyl-lA4-

3 butadiynediyl) .Q. The conversion of 2 to the alternating poly(heterocycle) poly(3,4-

didecyloxythiophene-2,5-diyl-2,5-thiophenediyl) .11 was accomplished with sodium sulfide

I nonahydrate [4]. The polymer it had limited solubility as compared with poly(3,4-

I didecyloxythiophene-2,5-diyl) [5]. The reaction of IQ with aniline [3] provided poly[3,4-

didecylothiophene-2,5-diyl-2,5-(N-phenylpyrrole)diyl] 12. All new compounds in this series

5 were fully characterized as reported in the Experimental section.

RO OR 1 roZnRO OR1) CBr4, Zn

OH SS Zý2) BuLi R R

ZHexane I8 R-=H1 3) CISi(CH 3)3 9 R -Si(CH 3)3

IuCI2,6-Lutidine

TMEDA

RO OR RO OR RO ORNa2S.9R2O

9S S PhNH2

.J.X=S, .1X.NPh

23,I

I

U" REFERENCES

1. Coffey, M., Reinhardt, B.A.,McKellar, B.R. and Feld, W.A., submitted for publication.

I 2. Corey, E.J. and Fuchs, P.L., Tetrehedron Letters, 1972, 36, 3769.

3. a) Bracke, W., J.Polym.Sci., A-i, 1972, 10, 975, b) Hay, A., J.Polym.Sci., A-4, 1969, 7,

975. 4. Beny, J-P, Dhawan, S.N., Kagan, J., Sundlass, S, J.Org.Chem., 1982, 47, 2201.

1 5. Unpublished results.

6. Vogel's Practical Organic Chemistry, 4th Ed., Longman, New York, NY, 1978, p. 302.

3 7. Kane, J.J., Gao, F., Evers, R.C., and Reinhardt, B.A., Polymer Preprints, 1992 33 (1)

1064.

IIIIIIIIIII

24

U

U

g APPENDIX 3

I ~MASSACHUSE'[Frs INSTITUTE OF TECHNOLOGY

ISubmitted by E.L. Thomas

I

UiIIiIIIUi.UIi

3U

Final Technical Report

AFOSR 90-0150

"Investigations of Nanoscale Composites and High Performance Polymers."

March 1, 1990 - February 28, 1993

3 E. L. Thomas

3 1.0 Abstract

During the past three years our research efforts have focussed upon the investigation of novel

3 nanoscale composites based on the self assembly of A/B block copolymer systems. In addition,

we examined several high performance polymers having outstanding electrical or mechanical

Sproperties. Our aim has been to establish processing/structure/property relationships by careful

study of sample morphology using a variety of structural characterization tools and correlating

the sample microstructure with processing conditions and observed properties.

I In order to optinize properties, we are learning how to process the samples to achieve controlled

size, shape and connectivity of the microstructural elements. One approach for achieving highly

3 ordered arrangements at the nanoscale level is to utilize thermodynamic self-assembly of diblock

copolymers or diblock copolymer/homopolymer blends wherein the mutual repulsion of the A

and B segments for typical molecular weights of 105 leads to periodic nanoscale structures.

Another approach is to have the block copolymer undergo self-assembly in a biased field. We

I have developed such a processing approach utilizing a roll casting technique that enables large

film (12 cm x 2 cm I mm) specimens of single crystal geometry to be fabricated and affords the

opportunity for samples to exhibit highly anisotropic properties.

3: High performance rigid-rod polymers have been developed by the Air Force which exhibit the

highest known values for tensile modulus and strength of any organic material. However, these

outstanding tensile properties are not matched in compression. Rigid-rod fibers fail in

compression by kink band formation. We have investigated the micromechanisms of kink band

I

I

formation and their relationship to compression strength and fiber microstructure in order to

learn how sample microstructure may be altered to improve compressive strength.

We have utilized the soluble precursor of poly-p-phenylene vinylene (PPV) which affords good

processability of film and fiber in order to relate sample microstructure to electrical properties.

Toward that goal, we have characterized crystal defects, such as grain boundary regions, in PPV

as well as in high modulus, high strength rigid-rod polymers through extensive use of high

resolution electron microscopy.

2.0 Detailed Progress of Researchers Funded by this Grant

A dominant factor in the determination of the domain morphology in A/B diblock copolymers is

area-minimization of the spatially periodic intermaterial surface, subject to fixed volume

fractions. The 3D geometry of such surfaces strongly influences material physical properties.

Nanocomposites based on block copolymers and block copolymer/homopolymer blends can

exhibit properties which are sensitive to the component(s) which have high phase connectivity.

For example, the double diamond microdomain morphology, associated with a newly discovered

family of triply periodic constant mean curvature surfaces, exhibits a tensile modulus which is

higher than either a lamellar cylindrical or spherical microdomain geometry at a fixed

3composition due to the 3rd dimensional connectivity of the double diamond phase network. A

doubly periodic boundary, corresponding to a classically known minimal surface (Scherk's First

3 Surface), was found to be a good model for the graon boundary region between lamellar

microdomains. This low energy grain boundary structure helps explain gas transport

I measurements in polygranule lamellar samples which exhibit connectivities higher than 2.

3 An improved technique for casting highly oriented films of block copolymers from solutions

subjected to flow was developed. Polymer solutions were rolled between two counter-rotating

adjacent cylinders while at the same time the solvent was allowed to evaporate. As the solvent

evaporated, the block copolymers microphase separated into globally oriented structures. WeUUI

I|

termed this new process "roll casting." The process has been applied to polystyrene-

polybutadiene-polystyrene (PS/PB/PS) triblock copolymer cast with and without additional high

molecular weight homopolymers. TEM and SAXS demonstrated that the pure copolymers films

consist of polystyrene cylinders assembled'on a hexagonal lattice in a polybutadiene matrix in a

near single crystal structure. Blends of copolymers with high molecular weight polystyrene

and/or polybutadiene, phase separated into ellipsoidal regions of homopolymer embedded in an

oriented block copolymer matrix. Annealing the films resulted in conversion of the

3 homopolymers regions to spheres accompanied by some misalignment of the copolymer

microdomains. We examined how processing parameters influence the resultant sample

3 microstructure. Preliminary measurements of mechanical properties (strt ;s-strain behavior) were

done on roll-cast samples as a function of applied strain with respect to the single crystal

3 microdomain geometry. The tensile modulus is quite sensitive to overall sample orientation and

correlates well with the orientational order parameter measured by 21D SAXS.

The crystal morphology of oriented films of poly (p-phenylene vinylene) (PPV) was investigated

3 using electron microscopy and X-ray diffraction. An X-ray diffraction rotation series confirmed

the existenct of fibre symmetry in bulk oriented filtns. Dark-field imaging by transmission

3electron microscopy revealed small diffracting regions of the order of 7 on in size with an aspect

ratio near 1. These diffracting regions were shown by high resolution transmission electron

3 microscopy to be composed of small crystallites with an average size of 5 dim. Imaging of the

lateral packing by HREM allowed the evaluation of local variations in crystallite orientation.

I This HREM method of orientation function determination compares well to bulk methods (e.g.

wide-angle X-ray scattering, infrared dichroism) for PPV of similar draw ratio. A micellar

model was developed to describe the crystalline morphology of oriented PPV. The model

depicts PPV z.s a highly connected network of small crystallites. The well-formed crystalline

regions are thought to compose approximately 50% of the sample volume with the remainder of

the volume being grain boundaries. Doping by AsFS led to the formation of am electron-dense

overlayer, thought to be arsenic oxide, which prohibited dark-field imaging of the crystallites.3II

II

After doping with H2304, crystallites of the electrically conductive phase were observed. The

general morphological character is preserved in the conversion from insulating to conducting

foams. For the conditions employed, the doped diffracting regions were 4 rim in size and

retained the orientation initially present in the pristine film.

Single crystals of poly(p-xylylene) were grown In dilute c,-methylnaphthalene solution and

studied by bright-field and high-resolution electron microscopy (HREM). The crystallization

process was discussed in terms of the dependence of crystal form on crystallization conditions.

A 0.15 =n resolution was achieved from high-resolution images of a frozen liquid crystalline

phase. High-temperature electron diffraction patterns confirmed the existence of the liquid-

crystalline phase in agreement with the previous work of Lieser. The HREM images show the

3- molecular packing in the snectic B phase.

I

I

IIIII

III

I IX. PUBLICATIONS, AFOSR/DARPA SUPPORTED

(March 1990 - February 1993)

1. Macromolecules 23, 4076-4082 (1990) (F.E. Karasz, T. Bleha and J. Gajdos)"Energetics of Strain-Induced Conformational Transitions in PolymethyleneChains".

2. Makromol. Chem. 191., 2111-2119 (1990) (F.E. Karasz, G. Guerra, P. Mustoand W.J. MacKnight) "Fourier Transform Infrared Spectroscopy of thePolymorphic Forms of Syndiotactic Polystyrene".

I 3. Journal of Liquid Chroma. 13, 2581-2591 (1990) (F.E. Karasz, N. Segudovicand W.J. MacKnight) "Solvent Effect on the Separation Mechanism inHPGPC of Polyimide and Polyethersulfone".

4. Materials Research Society Proceedings, 175, 315-324 (1990) (E.L. Thomas,3 S.P. Gido) "Periodic Area Minimization Surfaces in Microstructural Science"

5. J. Mat. Sci., 25, 311-320 (1990) (E.L. Thomas, M. Masse, D.C. Martin, J.Petermann and F.E. Karasz) "Crystal Morphology in Pristine and DopedFilms of Poly(p-phenylene vinylene)"

3 6. Polymer Preprints, 31(1) 455 (1990) (W.A. Feld, B. Kirk, M. Carren) "TheSynthesis of Poly(Ether Ether Ketone) (PEEK) Containing OxyethyleneUnits from an AB Monomer".

7. Polymer Preprints, 31(2), 681, (1990) (W.A. Feld and J.P. Chen) "TheSynthesis and Polymerization of a Rigid-Rod AB Monomer".

8. J. Chem. Mater., 2, 670 (1990) (W.A. Feld, M. Zhao, M. Samoc, P.N. Prasad,B.A. Reinhardt, M.R. Unroe, M. Prazak, R.C. Evers, J.J. Kane, C. Jariwalaand M. Sinsky) "Is There a Role for Organic Materials Chemistry inNonlinear Optics and Photonics".

3 9. Polymer Preprints, 31(2), 709-10 (1990) (W.A. Feld, J. J. Kane, R.C.Tomlinson) "New Approaches to Ehe Synthesis of N-Substituted3 Polybenzimidazoles".

10. New Polymeric Materials 2, 75-91 (1990) (F.E. Karasz, M. Masse, J. Hirschand V. White) "A Multi-Technique Investigation of AsF5-Doping Chemistryin Poly (p-phenylene vinylene).

11. J. Chem. Phys. 93, 7457-7462 (1990) (F.E. Karasz, Y. Guo and K. Langley)"Time Scale Dependence of Diffusion in Porous Material: Dynamic LightScattering and Computer Simulation".

U

I

3 12. Science in China, Series B, No. 5, 460-470 (1990) (F.E. Karasz, X. Jin, Y.Luo and R. Huo) "Thermal Degradation of Sulfonated PEEK".

3 13. Contemporary Topics In Polymer Science, Vol. 6., MultiphaseMacromolecular Systems (Bill M. Culbertson, Ed.), Plenum PressPublishers, New York, 493-504 (1989) (W.J. MacKnight, F.E. Karasz and S.Choe) "Phase Behavior in Miscible Polybenzimidazole/PolyetherimideBlends".

I 14. Proceedings of the Electrochemical Society, 88-6 747-753 (1988) (F.E.Karasz, J.B. Schlenoff and J. M. Machado) "Improved Mass Transport in3 Rechargeable Electrodes Employing Conducting Polymer Blends".

15. MRS Proceedings, Volume 171, Materials Research Society, Pittsburgh, 197-202 (1990) D.W. Schaefer, J.E. Mark, Eds., (F.E. Karasz, H. Yamaoka, N.Aubrey, W.J. MacKnight) "Miscibility in Blends of Polybenzimidazole andFluorine Containing Polyinides".

16. Acta Polymerica Sinica No. 4, 426-433 (1990) (F.E. Karasz, R. Huo, Y. Luo,L. Liang and X. Jin) "Kinetic Studies on Thermal Degradation of Poly(ArylEther Ether Ketone) and Sulfonated Poly(Aryl Ether Ether Ketone) byTGA".

17. Liquid Crystals 9, 47-57 (1991) (G.S. Attard, F.E. Karasz and C.T. Imrie)"Side-Chain Liquid Crystalline Copolymers Containing Charge Transfer

* Groups".

18. Polymer 32, 3-11 (1991) (F.E. Karasz, P. Musto, L. Wu, and W.J.MacKnight) "Fourier Transform Infrared Spectroscopy Investigations ofPolybenzimidazole/poly(bisphenol-A carbonate) Blends".

19. Polym. Comm, 32, 30-32 (1991) (F.E. Karasz, G. Guerra, C. De Rosa, V.M.Vitagliano, V. Petraccone and P. Corradini) "Blending Effects in thePolymorphism of Syndiotactic Polystyrene Crystallized from the Quenched3 Amorphous Phase".

20. Liquid Crystals, 9, 307-320, (1991) (F.E. Karasz, A. Nazemi, E.J.C. Kellarand G. Williams) "Electric Field Induced AC Alignment and Realignment: AStudy of A Liquid-Crystalline Copolymer Having Longitudinally andLaterally Attached Mesogenic Groups as Side Chains Monitored Through3 Dielectric Spectroscopy and Optical Thermomicroscopy".

21. Progress in Pacific Polymer Science, B.C. Anderson, Y. Imanishi (Eds.),3 Springer-Verlag Berlin, 213-225 (1991) (F.E. Karasz, K. Liang, L. Wu, J.Grebowicz and W.J. MacKnight) "Miscibility Behavior inPolyethersulfone/Polyimide Blends F.E. Karasz and without Solvents".

I

I

322. Polymer 32, 605-608 (1991) (F.E. Karasz, C.J. Wung, Y. Pang and P.N.Prasad) "Poly(p-phenylene vinylene)-Silica Composite: A Novel Sol-Gel3 Processed Non-Linear Optical Material for Optical Waveguides".

23. J. Polym. Sci.: Part B: Polymer Physics,29, 649-657 (1991) (F.E. Karasz, K.Liang, G. Banhegyi, and W.J. MacKnight) "Thermal, Dielectric, andMechanical Relaxation in Poly(benzimidazole)/Poly(etherimide) Blends".

24. Polym. Commun. 32, 185-188 (1991) (F.E. Karasz, W. Salomons and G. tenBrinke) "Copolymer Blends of Styrene and ortho-fluorostyrene".

25. Mechanical Behavior of Materials - VI. Masahiro Jono and Tatsuo Inoue,Editors, Pergamon Press, Tokyo, (1991), 263-268 (F.E. Karasz, Z. Chai andR. Sun) "Aspects of Miscibility in Copolymer Blends".

26. J. Macromol. Sci.-Chem. A27 (13 & 14), 1693-1712 (1990) (F.E. Karasz andH. Ueda) "Critical Miscibility Phenomena in Blends of Chlorinated

3Polyethylenes".

27. Polym. Plast. Technol. Eng., 30 (2 & 3), 183-225 (1991) (F.E. Karasz, G.Banhegyi, P. Hedvig, Z. Petrovic) "Applied Dielectric Spectroscopy ofPolymeric Composites".

3 28. Polymer 32, 2363-2366, (1991) (F.E. Karasz and W. Liang), "MolecularOrientation of Highly Drawn Poly(p-2-methoxyphenylene vinylene)"

3 29. Makromol. Chem. 192, 1495-1508 (1991) (G. Attard, F.E. Karasz, J. S. Dave,A. Wallington, C.T. Imrie), "Transitional Properties of Liquid-crystalline3 Side-chain Polymers Derived from Poly(p-hydroxystyrene)'.

30. Synthetic Met. 41, 341 (1991) (F.E. Karasz, M. J. Winokur and D. Chen),3 "Structural Studies of Alkali-doped Poly(p-phenylene vinylene)".

31. Polym. Eng. and Sci. 31, 936-943 (1991) (F.E. Karasz, S. Havriliak and G.Banhegyi), "Determination of Unblended Chain Dynamic Parameters of aPolar Discontinuous Phase in an Immiscible Polymer Blend".

32. Polym. Eng. and Sci. 31, 981-987 (1991) (F.E. Karasz, J.H. Kim and M.F.Malone) "Effects of Phase Separation on the Mechanical Properties ofPolystyrene/Poly(vinyl methyl ether) Blends".

33. Macromolecules, 24, 4762-4769 (1991) (W.J. MacKnight, F.E. Karasz, P.Musto), "Hydrogen Bonding in Polybenzimidazole/Poly(ether imide) Blends:3 A Spectroscopic Study".

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I3 34. Macromolecules, 24, 48204822 (1991) (F.E. Karasz, A. Bielecki, D.P.

Burum, and D.M. Rice), "Solid-State Two-Dimensional '3C-'H Correlation(HETCOR) NMR Spectrum of Amorphous Poly(2,6-dimethyl-p-phenyleneoxide)".

I 35. J. Polym. Sci.: Part B: Polym. Physics, 29 1389-1395 (1991) (F.E. Karasz, P.Cifra and W.J. MacKnight), "Short-Range Order in Miscible PolymerBlends: A Monte Carlo Study".

1 36. Macromolecules, 24, 5134-5140 (1991) (F.E. Karasz, G. Williams, A.Nazemi, J.S. Hill, D. Lacey and G.W. Gray), "Dielectric RelaxationProperties and Alignment Behavior of a Liquid-Crystalline Polymer HavingLaterally Attached Mesogenic Groups".

I 37. Polymer, 32 2340-2344 (1991) (F.E. Karasz, J. H. Simpson and D. M. Rice),"Investigation of H2SO4-doped, Ring-Deuterated Poly(p-phenylene vinylene)Using Solid State 'H Quadrupole Echo NMR Spectroscopy".

38. Chemistry of Materials, 3, 941-947 (1991) (F.E. Karasz, R. K. McCoy, A.Sarker and P. M. Lahti) "Synthesis and Characterization of Ring-Halogenated Poly(1,4-phenylene vinylenes)".

39. Polymer Communications, 32, 430-432 (1991) (F.E. Karasz, G. Guerra, M.Iuliano, A. Grassi, D. M. Rice and W. J. MacKnight) "Solid-State High-Resolution `3C Nuclear Magnetic Resonance Spectra of Syndiotactic Poly(p-methyl styrene)".

40. Phys. Review B, 44, 2507-2515 (1991) (F.E. Karasz, P. A. Heiney, J. E.Fischer, D. Djurado, J. Ma, D. Chen, M. J. Winokur, N. Coustel and P.Bernier) "Channel Structures in Alkali-Doped Conjugated Polymers:Broken-Symmetry 2-D Intercalation Superlattices".

I 41. MRS Proceedings Vol. 227, 335-340 (1991) (F.E. Karasz, J. L. Goldfarb, R. J.Farris, and Z. Chai) "A Calorimetric Evaluation of the Peel Adhesion Test".

I 42. J. Polym. Sci.: Part B: Polym. Physics, 30, 11-18, (1992) (F.E. Karasz, J. H.Simpson and D. M. Rice) "2H NMR Characterization of Phenylene Ring FlipMotion in Poly(p-phenylene vinylene) Films".

43. J. Polym. Sci.: Part B: Polym. Physics, 30, 49-60, (1992) (W. J. MacKnight,F.E. Karasz and S. Cimmino) "Miscibility and Phase Behavior in AtacticPolystyrene and Poly (o-chlorostyrene-co-p-chlorostyrene) Blends: Effect ofPolystyrene Molecular Weight and Copolymer Composition".I

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44. Polymer Bulletin, 2-7, 261-266 (1991) (F.E. Karasz, J.S. Rutt and Y.Takahashi) "Phase Behavior of Thermotropic Liquid Crystalline/ConductingPolymer Blends".

45. Polymer Preprints 32, 232-233 (1991) (J.J. Kane and W. Qian) "Synthesis ofN-Substituted Polybenzimidazoles byCyclodehydrogenation of PrecursorPoly(Schiff Bases)".

46. Polymer Preprints 33, 1064-1065 (1992) (J.J. Kanc, F. Gao, B.A. Reinhardtand R.C. Evers) "Synthesis of a Series of Conjugated EnynePolythiophenes".

I 47. Polymer Communications 32, 4883487 (1991) (E.L. Thomas and W. Zhang)"Monomer Image of Poly(p-xylylene) Crystal at 0.18 Nanometer Resolution".

1 48. Journal of Polymer Science (Physics), 30, 1285-1290 (1992) (E.L. Thomasand W. Zhang) "Direct Imaging of Smectic B Phase of Poly(p-Xylyene)".

49. Macromolecules, 25, 192-194 (1992) (F.E. Karasz, P. Cifra and W. J.MacKnight) "Expansion of Polymer Coils in Miscible Polymer Blends ofAsymmetric Composition".

50. Macromolecules, 25, 1057-1061 (1992) (F.E. Karasz, W. Huh) "MiscibilityBehavior in Blends of Poly(acrylonitrile-co-butadiene) and ChlorinatedPoly(vinyl chloride)".

51. Macromolecules, 25, 743-749 (1992) (F.E. Karasz, H. Mattoussi and S.O'Donohue) "Polyion Conformation and Second Virial CoefficientDependencies on the Ionic Strength for Flexible Polyelectrolyte Solutions".

52. Macromolecules, 25, 1278-1283 (1992) (F.E. Karasz, C.T. Imrie and G.S.Attard) "Side-Chain Liquid-Crystalline Copolymers Containing Spacers ofDiffering Lengths".

53. Netsu Sokutei, 19 (1), 2-10 (1992) (F.E. Karasz, P. Cifra) "The Effect ofInteractions in Polymer Blends Studied by Monte Carlo Simulations".

54. Phys. Rev. B., 45 (5), 2035-2045 (1992) (F.E. Karasz, D. Chen, M.J.Winokur, Y. Cao and A.J. Heeger) "Stage-1 Phases of Alkali Metal-DopedConducting Polymers".

1 55. J. Polym. Sci.: Part B: Polymer Physics, 30, 465-476 (1992) (F.E. Karasz, K.Liang, J. Grebowicz, E. Valles, and W.J. MacKnight) "Thermal and3 Rheological Properties of Miscible Polyethersulfone/Polyimide Blends".

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I56. ANTEC '92, p. 585, "Rheology and Mechanical Properties of Ultrahigh

Performance Polyimide Melt Blends", K. G. Blizard, M.A. Druy, and F.E.Karasz (1992).

57. Integration of Fundamental Polymer Science and Technology-5, P.J.Lemstra and L.A. Kleintjens, Editors, Elsevier Pub. (1991) 3-11 (F.E.Karasz and W.J. MacKnight), "Phase-Behavior in Polymer Blends: TheEffect of Microstructure".

1 58. Colloid & Polymer Science, 270, 113-127 (1992) (B. Banhegyi, F.E. Karasz,G. Marosi and G. Bertalan) "Studies of Thermally Stimulated Currents inPolypropylene/Calcium Carbonate/Surfactant Systems".

59. Frontiers of Polymer Research, P.N. Prasad and J.K. Nigam, Eds., PlenumPress (1991) 489-495 (W.J. MacKnight, F.E. Karasz and H.S. Kang)"Dynamic Mechanical and Dielectric Properties of Sulfonylated Poly(2,6-Dimethyl-1,4-Phenylene Oxide) Copolymers".I

60. Macromolecules, 25, 2099-2106 (1992) (F.E. Karasz, J.H. Simpson and D.M.Rice) "Characterization of Chain Orientation in Drawn Poly(p-phenylenevinylene) by 2H Quadrupole Echo NMR Spectroscopy".

3 61. Phys. Rev. A, 45, 5426-5446 (1992) (F.E. Karasz and I. Teraoka) "One-dimensional Diffusion with Stochastic Random Barriers".

62. Polymer Communications, 33, 1780-1782 (1992) (W.B. Liang, D.M. Rice,F.E. Karasz, F.R. Denton III and P.M. Lahti) "Preparation of Poly(p-phenylene vinylene) Deuterium Labelled in the Vinylene Positions".

63. J. Polym. Sci.: Part A: Polymer Chemistry, 30, 1227-1231 (1992) (F.E.Karasz, L. Litauszki, K. Grtinberg, and W. Berger) "Thermal Behavior ofCopolyimides Containing Bisbenzoylamine Groups".

64. Macromolecules, 25, 3068-3074 (1992) (F.E. Karasz, J.H. Simpson, W. Liangand D.M. Rice) "Solid-State 2H Quadrupole Echo NMR Characterization ofVinylene-Deuterated Poly(p-phenylene vinylene) Films".

1 65. Chemical Processing of Advanced Materials, John Wiley & Sons, New York,637-646 (1992) (G.S. Attard, F.E. Karasz and C.T. Imrie) "Multifunctional

* Polymers".

66. Chemical Processing of Advanced Materials, John Wiley & Sons, New York,647-662 (1992) (F.E. Karasz and R.Ma.S. Gregorius) "Developments in theSynthesis of Polyarylene Vinylenes".

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I67. Macromolecules, 25, 4175-4181 (1992) (Diane B. Scott, F.E. Karasz, Alan J.

Waddon, Je-Gang Lin and H. Henning Winter) "Shear-Induced Orientation"Transitions in Triblock Copolymer of Styrene-Butadiene-Styrene withCylindrical Domain Morphology"

68. Polym. Eng. and Sci., 32, 1047-1051 (1992) (F.E. Karasz, B. deJong, A.J.Waddon and W.J. MacKnight) "Blending of Poly(benzimidazole) (PBI) Witha Low Molecular Weight Ether Imide Model Compound"

69. New Polymeric Materials, 3, 163-173 (1992) (F.E. Karasz, K. Jeremic andW.J. MacKnight) "Influence of Solvent and Temperature on the PhaseBehavior of Polyarylsulfone/Polyimide Blends".

70. Polymer, 33, 3101-3107 (1992) (W.B. Liang, F.E. Karasz and M. A. Masse)"Highly Conductive Crystalline Poly(2-methoxy-p-phenylene vinylene)".

71. Polymer, 33, 3116-3122 (1992) (F.E. Karasz, D. Chen, M.J. Winokur andM.A. Masse) "A Structural Study of Poly(p-phenylene vinylene)".

72. J. Polym. Sci. A., Polym. Chem., 30, 2223-2231 (1992) (F.E. Karasz, F.R.Denton III and P.M. Lahti) "The Effect of Radical Trapping Reagents UponFormation of Poly(a-Tetrahydrothiophenio para-xylylene) Polyelectrolytes bythe Wessling Soluble Precursor Method".

73. J. Polym. Sci. A., Polym. Chem., 30, 2233-2240 (1992) (F.E. Karasz, F.R.Denton III, A. Sarker, P.M. Lahti and R.O. Garay) "Para-Xylylenes andAnalogues by Base-Induced Elimination from 1,4-Bis-(Dialkylsulfoniomethyl)arene Salts in Poly(1,4-Arylene Vinylene) Synthesisby the Wessling Soluble Precursor Method".

74. Polymer, 33, 3388-3393 (1992) (F.E. Karasz, V. Janarthanan and W.J.MacKnight) "Miscibility in Polybenzimidazole/Polyimide Sulfone Blends: AComparison of Blends Containing Fluorinated and Non-fluorinatedPolyimide Sulphone".

75. Macromolecules, 25, 4716-4720 (1992) (F.E. Karasz and Z. Chai) "Miscibilityin (A-B)/C-D) Copolymer Blends".

76. Polymer, 33, 3783-3789 (1992) (F.E. Karasz and A.J. Waddon) "Crystallineand Amorphous Morphologies of an Aromatic Polyimide Formed onPrecipitation from Solution".

77. Phys. Rev. A, 46, 3335-3342 (1992) (F.E. Karasz, Y. Guo, S.J. O'Donohue,and K.H. Langley) "Polymer Diffusion in Porous Media of Fumed SilicaStudied by Forced Rayleigh Scattering".

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78. Macromolecules, 25, 4902-4904 (1992) (F.E. Karasz, Y. Guo and KH.LangleyY'Restricted Diffusion of Highly Dense Starburst-DendriticPoly(amido amine) in Porous Glasses".

79. Macromolecules, 25, 4895-4901 (1992) (F.E. Karasz, P. Cifra and W.J.MacKnight) "Surface Segregation in Polymer Blends: A Monte CarloSimulation".

80. MRS Proceedings Vol. 248, 477-482 (1992) (H. Mattoussi, F.E. Karasz andS. O'Donohue) "Static and Hydrodynamic Dimensions of Flexible Polyions inSolutions".

I 81. J. Serb. Chem. Soc. 57, 653-661 (1992) (R. Stankovic, F.E. Karasz and R.W.Lenz) "Electrical Conductivity of Doped Poly(Butadiene-co-2-vinyl Pyridine)Diblock Copolymers: Macrostructured Polymeric Semiconductors".

82. J. Polym. Sci. 30, 1401-1407 (1992) (W.J. MacKnight, F.E. Karasz and P.3 Cifra) "Polymer Miscibility in Capillaries".

83. Phys. Rev. B 46, 9320-9324 (1992) (F.E. Karasz, E.L. Frankevich, A.A.Lymarev, I. Sokolik, S. Blumstengel, R.H. Baughman and H. H. Horhold)"Polaron-pair Generation in Poly(phenylene vinylenes)".

84. Polymers for Advanced Technologies, 3, 157-168 (1992) (F.E. Karasz, A.Nazemi, G. Williams and G.S. Attard) "The Alignment of LC Side-chainPolymers in Directing Electric Fields: Theory and Practice".

85. Macromolecules, 25, 6106-6112 (1992) (F.E. Karasz, I. Teraoka and K.H.Langley) "Reptation Dynamics of Semirigid Polymers in Porous Media".

86. Macromolecules, 25, 6113-6118 (1992) (F.E. Karasz, Z. Chai and R. Sun)"Miscibility in Blends of Copolymers: Sequence Distribution Effects".

87. Macromolecules, 25, 6664-6669 (1992) (F.E. Karasz, R. Gregorius and P.M.Lahti) "Preparation and Characterization of Poly(arylenevinylene)Copolymers and Their Blends".

I 88. Chemistry of Materials, 4. 1246-1253 (1992) (F.E. Karasz, G.S. Attard andC.T. Imrie) "Low Molar Mass Liquid-Crystalline Glasses: Preparation andProperties of the a-(4-Cyanobiphenyl-4'-oxy)-&o-(1-pyreniminebenzylidene-4'-oxy)alkanes".

89. Synthetic Metals, 5, 11-19 (1992) (F.E. Karasz and R. Gregorius)3 "Conduction in Poly(arylene vinylene) Copolymers and Blends".

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I 90. Eur. Polym. J., 29, 159-162 (1993) (F.E. Karasz and R. Gregorius)"Orientation in Poly(Arylene Vinylene) Copolymers and Blends: An3 Infrared Dichroism Study".

91. Polymer Journal, 12, 1363-1369 (1992) (F.E. Karasz, Hiroyoshi Ueda)"Miscibility in Blends of Chlorinated Polyethylene and ChlorinatedPoly(vinyl chloride)".

92. Polymer 34, 214-217 (1993) (F.E. Karasz, S. Cimmino, E.D. Pace, E.Martuscelli, C. Silvestre, D.M. Rice) "Miscibility of SyndiotacticPolystyrene/Poly(vinyl methyl ether) Blends".

I 93. Macromolecules, 26, 177-181 (1993) (F.E. Karasz and Antonin Sikora)"Solution-Phase Equilibria for Block Copolymers in Selective Solvents".

94. J. Chem. Phys. 98, 712-716 (1993) (F.E. Karasz, G. Mao, J.E. Fischer andM.J. Winokur) "Nonplanarity and Ring Torsion in Poly(p-phenylenevinylene): A Neutron-Diffraction Study".

95. J. Polym. Sci., Polym. Phys. Ed., 31, 37-46 (1993) (E.L. Thomas and R.Albalak) "Microphase Separation of Block Copolymer Solutions in FlowField".

I 96. J. Polym. Sci., Polym. Phys. Ed., (E.L. Thomas and R.J. Albalak) "RollCasting ofBlock Copolymers and of Block Copolymer-Homopolymer Blends"

I (in press).

97. Macromolecules, (E.L. Thomas, P. Pradere and W. Zhang) "Direct Imagingof Molecular Steps on Polymer Single Crystal Surfaces" (in press).

98. "Kinking in PBZT Fibers" (in press).

1 99. "The Application of Low Voltage High Resolution SEM to the Study ofPolymer Morphology" (in press).

1 100. J. Appl. Polym. Sci., "Preparation and Characterization of AromaticPolyimides and Related Copolymers" (in press).

I 101. Macromolecules, "Diffusion of Polystyrene in Controlled Pore Glasses:Transition from the Dilute to the Semidilute Regime" (in press).

I 102. J. Appl. Polym. Sci., "The Interaction of Water with PolyurethanesContaining Block Copolymer Soft Segments" (in press).

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103. Macromolecules, "Dependence of the Transitional Properties of Polystyrene-Based Side-Chain Liquid-Crystalline Polymers on the Chemical Nature ofthe Mesogenic Group" (in press).

104. Macromolecules, "Comparison of the Mesogenic Properties of Monomeric,Dimeric, and Side-Chain Polymeric Liquid Crystals" (in press).

105. Polymer International, "Solution Properties of Poly(fluorostyrene-co-chlorostyrene) Copolymers. I. Light Scattering, Differential Refractometryand Viscometry" (in press).

106. Polymer International, "Solution Properties of Poly(fluorostyrene-co-chlorostyrene) Copolymers. II. High-performance Gel PermeationChromatography" (in press).

I 107. Polymer International, "Structure in Mesogenic Diol-containing Polyesters"

(in press).

108. Macromolecules, "A Soluble Blue-Light-Emitting Polymer" (in press).

109. Polymer, "Isotactic Polypropylene/Hydrogenated Oligo(Cyclopentadiene)Blends: Phase Diagram and Dynamic-mechanical Behaviour of ExtrudedIsotropic Films" (in press).

110. Polymer, "Miscibility in Blends of Sulfonylated Poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) with Homopolymers of Halogen-substitutedStyrene Derivatives" (in press).

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